diff --git a/IntegrationTests/allocation-counter-tests-framework/run-allocation-counter.sh b/IntegrationTests/allocation-counter-tests-framework/run-allocation-counter.sh
index 7a828934b5..dea2298968 100755
--- a/IntegrationTests/allocation-counter-tests-framework/run-allocation-counter.sh
+++ b/IntegrationTests/allocation-counter-tests-framework/run-allocation-counter.sh
@@ -296,8 +296,9 @@ build_package \
 set -eu
 cd "$working_dir"
 swift build "${build_opts[@]}"
+build_dir=$(swift build "${build_opts[@]}" --show-bin-path)
 for f in "${files[@]}"; do
     echo "- $f"
-    swift run "${build_opts[@]}" "$(module_name_from_path "$f")"
+    "${build_dir}/$(module_name_from_path "$f")"
 done
 )
diff --git a/IntegrationTests/allocation-counter-tests-framework/template/scaffolding.swift b/IntegrationTests/allocation-counter-tests-framework/template/scaffolding.swift
index ca102aa1e8..924ad2bd38 100644
--- a/IntegrationTests/allocation-counter-tests-framework/template/scaffolding.swift
+++ b/IntegrationTests/allocation-counter-tests-framework/template/scaffolding.swift
@@ -13,6 +13,7 @@
 //===----------------------------------------------------------------------===//
 
 import AtomicCounter
+import Dispatch
 import Foundation
 
 #if canImport(Darwin)
@@ -139,7 +140,14 @@ func measureAll(trackFDs: Bool, _ fn: () -> Int) -> [Measurement] {
 }
 
 func measureAndPrint(desc: String, trackFDs: Bool, fn: () -> Int) {
+    let start = DispatchTime.now()
     let measurements = measureAll(trackFDs: trackFDs, fn)
+
+    let end = DispatchTime.now()
+    let durationNanos = end.uptimeNanoseconds - start.uptimeNanoseconds
+    let durationSeconds = Double(durationNanos) / 1e9
+    print("\(desc).duration: \(durationSeconds) (s)")
+
     measurements.printTotalAllocations(description: desc)
     measurements.printRemainingAllocations(description: desc)
     measurements.printTotalAllocatedBytes(description: desc)
diff --git a/IntegrationTests/tests_04_performance/Thresholds/5.10.json b/IntegrationTests/tests_04_performance/Thresholds/5.10.json
index 29a7bf1e7c..2e40ec05a1 100644
--- a/IntegrationTests/tests_04_performance/Thresholds/5.10.json
+++ b/IntegrationTests/tests_04_performance/Thresholds/5.10.json
@@ -19,8 +19,8 @@
     "1000_udp_reqs": 6050,
     "1000_udpbootstraps": 2050,
     "1000_udpconnections": 75050,
-    "1_reqs_1000_conn": 384050,
-    "assume_isolated_scheduling_10000_executions": 89,
+    "1_reqs_1000_conn": 384000,
+    "assume_isolated_scheduling_10000_executions": 11,
     "bytebuffer_lots_of_rw": 2050,
     "creating_10000_headers": 0,
     "decode_1000_ws_frames": 2050,
@@ -33,8 +33,8 @@
     "encode_1000_ws_frames_new_buffer_with_space": 3050,
     "encode_1000_ws_frames_new_buffer_with_space_with_mask": 5050,
     "execute_hop_10000_tasks": 0,
-    "flat_schedule_10000_tasks": 100100,
-    "flat_schedule_assume_isolated_10000_tasks": 90100,
+    "flat_schedule_10000_tasks": 120050,
+    "flat_schedule_assume_isolated_10000_tasks": 110050,
     "future_assume_isolated_lots_of_callbacks": 74050,
     "future_erase_result": 4050,
     "future_lots_of_callbacks": 74050,
@@ -46,14 +46,14 @@
     "modifying_byte_buffer_view": 6050,
     "ping_pong_1000_reqs_1_conn": 314,
     "read_10000_chunks_from_file": 110050,
-    "schedule_10000_tasks": 40100,
+    "schedule_10000_tasks": 50050,
     "schedule_and_run_10000_tasks": 50050,
-    "schedule_assume_isolated_10000_tasks": 40100,
-    "schedule_with_deadline_10000_tasks": 40100,
-    "schedule_with_deadline_assume_isolated_10000_tasks": 40100,
-    "scheduling_10000_executions": 89,
-    "submit_10000_tasks": 20100,
-    "submit_assume_isolated_10000_tasks": 20100,
+    "schedule_assume_isolated_10000_tasks": 50050,
+    "schedule_with_deadline_10000_tasks": 50050,
+    "schedule_with_deadline_assume_isolated_10000_tasks": 50050,
+    "scheduling_10000_executions": 11,
+    "submit_10000_tasks": 20050,
+    "submit_assume_isolated_10000_tasks": 20050,
     "udp_1000_reqs_1_conn": 6200,
     "udp_1_reqs_1000_conn": 162050
 }
diff --git a/IntegrationTests/tests_04_performance/Thresholds/5.9.json b/IntegrationTests/tests_04_performance/Thresholds/5.9.json
index 2d8cb07bff..f230a3cace 100644
--- a/IntegrationTests/tests_04_performance/Thresholds/5.9.json
+++ b/IntegrationTests/tests_04_performance/Thresholds/5.9.json
@@ -20,7 +20,7 @@
     "1000_udpbootstraps": 2050,
     "1000_udpconnections": 75050,
     "1_reqs_1000_conn": 393050,
-    "assume_isolated_scheduling_10000_executions": 89,
+    "assume_isolated_scheduling_10000_executions": 11,
     "bytebuffer_lots_of_rw": 2050,
     "creating_10000_headers": 0,
     "decode_1000_ws_frames": 2050,
@@ -33,8 +33,8 @@
     "encode_1000_ws_frames_new_buffer_with_space": 3050,
     "encode_1000_ws_frames_new_buffer_with_space_with_mask": 5050,
     "execute_hop_10000_tasks": 0,
-    "flat_schedule_10000_tasks": 100100,
-    "flat_schedule_assume_isolated_10000_tasks": 90100,
+    "flat_schedule_10000_tasks": 120050,
+    "flat_schedule_assume_isolated_10000_tasks": 110050,
     "future_assume_isolated_lots_of_callbacks": 74050,
     "future_erase_result": 4050,
     "future_lots_of_callbacks": 74050,
@@ -46,14 +46,14 @@
     "modifying_byte_buffer_view": 6050,
     "ping_pong_1000_reqs_1_conn": 329,
     "read_10000_chunks_from_file": 110050,
-    "schedule_10000_tasks": 40100,
+    "schedule_10000_tasks": 50050,
     "schedule_and_run_10000_tasks": 50050,
-    "schedule_assume_isolated_10000_tasks": 40100,
-    "schedule_with_deadline_10000_tasks": 40100,
-    "schedule_with_deadline_assume_isolated_10000_tasks": 40100,
-    "scheduling_10000_executions": 89,
-    "submit_10000_tasks": 20100,
-    "submit_assume_isolated_10000_tasks": 20100,
+    "schedule_assume_isolated_10000_tasks": 50050,
+    "schedule_with_deadline_10000_tasks": 50050,
+    "schedule_with_deadline_assume_isolated_10000_tasks": 50050,
+    "scheduling_10000_executions": 11,
+    "submit_10000_tasks": 20050,
+    "submit_assume_isolated_10000_tasks": 20050,
     "udp_1000_reqs_1_conn": 6200,
     "udp_1_reqs_1000_conn": 162050
 }
diff --git a/IntegrationTests/tests_04_performance/Thresholds/6.0.json b/IntegrationTests/tests_04_performance/Thresholds/6.0.json
index 0870e33436..2e40ec05a1 100644
--- a/IntegrationTests/tests_04_performance/Thresholds/6.0.json
+++ b/IntegrationTests/tests_04_performance/Thresholds/6.0.json
@@ -20,7 +20,7 @@
     "1000_udpbootstraps": 2050,
     "1000_udpconnections": 75050,
     "1_reqs_1000_conn": 384000,
-    "assume_isolated_scheduling_10000_executions": 89,
+    "assume_isolated_scheduling_10000_executions": 11,
     "bytebuffer_lots_of_rw": 2050,
     "creating_10000_headers": 0,
     "decode_1000_ws_frames": 2050,
@@ -33,8 +33,8 @@
     "encode_1000_ws_frames_new_buffer_with_space": 3050,
     "encode_1000_ws_frames_new_buffer_with_space_with_mask": 5050,
     "execute_hop_10000_tasks": 0,
-    "flat_schedule_10000_tasks": 100100,
-    "flat_schedule_assume_isolated_10000_tasks": 90100,
+    "flat_schedule_10000_tasks": 120050,
+    "flat_schedule_assume_isolated_10000_tasks": 110050,
     "future_assume_isolated_lots_of_callbacks": 74050,
     "future_erase_result": 4050,
     "future_lots_of_callbacks": 74050,
@@ -46,14 +46,14 @@
     "modifying_byte_buffer_view": 6050,
     "ping_pong_1000_reqs_1_conn": 314,
     "read_10000_chunks_from_file": 110050,
-    "schedule_10000_tasks": 40100,
+    "schedule_10000_tasks": 50050,
     "schedule_and_run_10000_tasks": 50050,
-    "schedule_assume_isolated_10000_tasks": 40100,
-    "schedule_with_deadline_10000_tasks": 40100,
-    "schedule_with_deadline_assume_isolated_10000_tasks": 40100,
-    "scheduling_10000_executions": 89,
-    "submit_10000_tasks": 20100,
-    "submit_assume_isolated_10000_tasks": 20100,
+    "schedule_assume_isolated_10000_tasks": 50050,
+    "schedule_with_deadline_10000_tasks": 50050,
+    "schedule_with_deadline_assume_isolated_10000_tasks": 50050,
+    "scheduling_10000_executions": 11,
+    "submit_10000_tasks": 20050,
+    "submit_assume_isolated_10000_tasks": 20050,
     "udp_1000_reqs_1_conn": 6200,
     "udp_1_reqs_1000_conn": 162050
 }
diff --git a/IntegrationTests/tests_04_performance/Thresholds/6.1.json b/IntegrationTests/tests_04_performance/Thresholds/6.1.json
index 0870e33436..6ddcb66fc7 100644
--- a/IntegrationTests/tests_04_performance/Thresholds/6.1.json
+++ b/IntegrationTests/tests_04_performance/Thresholds/6.1.json
@@ -19,8 +19,8 @@
     "1000_udp_reqs": 6050,
     "1000_udpbootstraps": 2050,
     "1000_udpconnections": 75050,
-    "1_reqs_1000_conn": 384000,
-    "assume_isolated_scheduling_10000_executions": 89,
+    "1_reqs_1000_conn": 384050,
+    "assume_isolated_scheduling_10000_executions": 11,
     "bytebuffer_lots_of_rw": 2050,
     "creating_10000_headers": 0,
     "decode_1000_ws_frames": 2050,
@@ -33,8 +33,8 @@
     "encode_1000_ws_frames_new_buffer_with_space": 3050,
     "encode_1000_ws_frames_new_buffer_with_space_with_mask": 5050,
     "execute_hop_10000_tasks": 0,
-    "flat_schedule_10000_tasks": 100100,
-    "flat_schedule_assume_isolated_10000_tasks": 90100,
+    "flat_schedule_10000_tasks": 120050,
+    "flat_schedule_assume_isolated_10000_tasks": 110050,
     "future_assume_isolated_lots_of_callbacks": 74050,
     "future_erase_result": 4050,
     "future_lots_of_callbacks": 74050,
@@ -46,14 +46,14 @@
     "modifying_byte_buffer_view": 6050,
     "ping_pong_1000_reqs_1_conn": 314,
     "read_10000_chunks_from_file": 110050,
-    "schedule_10000_tasks": 40100,
+    "schedule_10000_tasks": 50050,
     "schedule_and_run_10000_tasks": 50050,
-    "schedule_assume_isolated_10000_tasks": 40100,
-    "schedule_with_deadline_10000_tasks": 40100,
-    "schedule_with_deadline_assume_isolated_10000_tasks": 40100,
-    "scheduling_10000_executions": 89,
-    "submit_10000_tasks": 20100,
-    "submit_assume_isolated_10000_tasks": 20100,
+    "schedule_assume_isolated_10000_tasks": 50050,
+    "schedule_with_deadline_10000_tasks": 50050,
+    "schedule_with_deadline_assume_isolated_10000_tasks": 50050,
+    "scheduling_10000_executions": 11,
+    "submit_10000_tasks": 20050,
+    "submit_assume_isolated_10000_tasks": 20050,
     "udp_1000_reqs_1_conn": 6200,
     "udp_1_reqs_1000_conn": 162050
 }
diff --git a/IntegrationTests/tests_04_performance/Thresholds/nightly-main.json b/IntegrationTests/tests_04_performance/Thresholds/nightly-main.json
index a5ce735741..d53f02417b 100644
--- a/IntegrationTests/tests_04_performance/Thresholds/nightly-main.json
+++ b/IntegrationTests/tests_04_performance/Thresholds/nightly-main.json
@@ -19,8 +19,8 @@
     "1000_udp_reqs": 6050,
     "1000_udpbootstraps": 2050,
     "1000_udpconnections": 75050,
-    "1_reqs_1000_conn": 384050,
-    "assume_isolated_scheduling_10000_executions": 89,
+    "1_reqs_1000_conn": 384000,
+    "assume_isolated_scheduling_10000_executions": 11,
     "bytebuffer_lots_of_rw": 2050,
     "creating_10000_headers": 0,
     "decode_1000_ws_frames": 2050,
@@ -33,8 +33,8 @@
     "encode_1000_ws_frames_new_buffer_with_space": 3050,
     "encode_1000_ws_frames_new_buffer_with_space_with_mask": 5050,
     "execute_hop_10000_tasks": 0,
-    "flat_schedule_10000_tasks": 100100,
-    "flat_schedule_assume_isolated_10000_tasks": 80100,
+    "flat_schedule_10000_tasks": 120050,
+    "flat_schedule_assume_isolated_10000_tasks": 110050,
     "future_assume_isolated_lots_of_callbacks": 74050,
     "future_erase_result": 4050,
     "future_lots_of_callbacks": 74050,
@@ -46,14 +46,14 @@
     "modifying_byte_buffer_view": 6050,
     "ping_pong_1000_reqs_1_conn": 314,
     "read_10000_chunks_from_file": 110050,
-    "schedule_10000_tasks": 40100,
+    "schedule_10000_tasks": 50050,
     "schedule_and_run_10000_tasks": 50050,
-    "schedule_assume_isolated_10000_tasks": 40100,
-    "schedule_with_deadline_10000_tasks": 40100,
-    "schedule_with_deadline_assume_isolated_10000_tasks": 40100,
-    "scheduling_10000_executions": 89,
-    "submit_10000_tasks": 20100,
-    "submit_assume_isolated_10000_tasks": 20100,
+    "schedule_assume_isolated_10000_tasks": 50050,
+    "schedule_with_deadline_10000_tasks": 50050,
+    "schedule_with_deadline_assume_isolated_10000_tasks": 50050,
+    "scheduling_10000_executions": 11,
+    "submit_10000_tasks": 20050,
+    "submit_assume_isolated_10000_tasks": 20050,
     "udp_1000_reqs_1_conn": 6200,
     "udp_1_reqs_1000_conn": 162050
 }
diff --git a/IntegrationTests/tests_04_performance/Thresholds/nightly-next.json b/IntegrationTests/tests_04_performance/Thresholds/nightly-next.json
index 29a7bf1e7c..6ddcb66fc7 100644
--- a/IntegrationTests/tests_04_performance/Thresholds/nightly-next.json
+++ b/IntegrationTests/tests_04_performance/Thresholds/nightly-next.json
@@ -20,7 +20,7 @@
     "1000_udpbootstraps": 2050,
     "1000_udpconnections": 75050,
     "1_reqs_1000_conn": 384050,
-    "assume_isolated_scheduling_10000_executions": 89,
+    "assume_isolated_scheduling_10000_executions": 11,
     "bytebuffer_lots_of_rw": 2050,
     "creating_10000_headers": 0,
     "decode_1000_ws_frames": 2050,
@@ -33,8 +33,8 @@
     "encode_1000_ws_frames_new_buffer_with_space": 3050,
     "encode_1000_ws_frames_new_buffer_with_space_with_mask": 5050,
     "execute_hop_10000_tasks": 0,
-    "flat_schedule_10000_tasks": 100100,
-    "flat_schedule_assume_isolated_10000_tasks": 90100,
+    "flat_schedule_10000_tasks": 120050,
+    "flat_schedule_assume_isolated_10000_tasks": 110050,
     "future_assume_isolated_lots_of_callbacks": 74050,
     "future_erase_result": 4050,
     "future_lots_of_callbacks": 74050,
@@ -46,14 +46,14 @@
     "modifying_byte_buffer_view": 6050,
     "ping_pong_1000_reqs_1_conn": 314,
     "read_10000_chunks_from_file": 110050,
-    "schedule_10000_tasks": 40100,
+    "schedule_10000_tasks": 50050,
     "schedule_and_run_10000_tasks": 50050,
-    "schedule_assume_isolated_10000_tasks": 40100,
-    "schedule_with_deadline_10000_tasks": 40100,
-    "schedule_with_deadline_assume_isolated_10000_tasks": 40100,
-    "scheduling_10000_executions": 89,
-    "submit_10000_tasks": 20100,
-    "submit_assume_isolated_10000_tasks": 20100,
+    "schedule_assume_isolated_10000_tasks": 50050,
+    "schedule_with_deadline_10000_tasks": 50050,
+    "schedule_with_deadline_assume_isolated_10000_tasks": 50050,
+    "scheduling_10000_executions": 11,
+    "submit_10000_tasks": 20050,
+    "submit_assume_isolated_10000_tasks": 20050,
     "udp_1000_reqs_1_conn": 6200,
     "udp_1_reqs_1000_conn": 162050
 }
diff --git a/IntegrationTests/tests_04_performance/test_01_allocation_counts.sh b/IntegrationTests/tests_04_performance/test_01_allocation_counts.sh
index 3c4a5a8840..dae1569268 100755
--- a/IntegrationTests/tests_04_performance/test_01_allocation_counts.sh
+++ b/IntegrationTests/tests_04_performance/test_01_allocation_counts.sh
@@ -45,8 +45,9 @@ observed_allocations="${observed_allocations}
 info "observed allocations:
 ${observed_allocations}"
 
+cat "$tmp/output"  # helps debugging
+
 for test in "${all_tests[@]}"; do
-    cat "$tmp/output"  # helps debugging
 
     while read -r test_case; do
         test_case=${test_case#test_*}
@@ -55,7 +56,7 @@ for test in "${all_tests[@]}"; do
         leaked_fds=$(grep "^test_$test_case.leaked_fds:" "$tmp/output" | cut -d: -f2 | sed 's/ //g')
         max_allowed_env_name="MAX_ALLOCS_ALLOWED_$test_case"
         max_allowed=$(jq '.'\""$test_case"\" "$here/Thresholds/$SWIFT_VERSION.json")
-        
+
         assert_is_number "$max_allowed" "Malformed or nonexistent ${SWIFT_VERSION}.json thresholds file"
 
         info "$test_case: allocations not freed: $not_freed_allocations"
diff --git a/IntegrationTests/tests_04_performance/test_01_resources/shared.swift b/IntegrationTests/tests_04_performance/test_01_resources/shared.swift
index 6677fdc016..d5abc590ea 100644
--- a/IntegrationTests/tests_04_performance/test_01_resources/shared.swift
+++ b/IntegrationTests/tests_04_performance/test_01_resources/shared.swift
@@ -18,7 +18,44 @@ import NIOHTTP1
 import NIOPosix
 
 let localhostPickPort = try! SocketAddress.makeAddressResolvingHost("127.0.0.1", port: 0)
-let group = MultiThreadedEventLoopGroup(numberOfThreads: System.coreCount)
+let group: MultiThreadedEventLoopGroup = {
+    preHeatMTELGSingleton()
+    return MultiThreadedEventLoopGroup.singleton
+}()
+
+extension MultiThreadedEventLoopGroup {
+    static var preheatedSingleton: MultiThreadedEventLoopGroup {
+        group
+    }
+}
+
+private func preHeatMTELGSingleton() {
+    for loop in MultiThreadedEventLoopGroup.singleton.makeIterator() {
+        var futures = [EventLoopFuture<Void>]()
+        futures.reserveCapacity(10_000)
+
+        for _ in 0..<10_000 {
+            let f = loop.submit {}
+            futures.append(f)
+        }
+
+        for f in futures {
+            try! f.wait()
+        }
+
+        var scheduleds = [Scheduled<Void>]()
+        scheduleds.reserveCapacity(10_000)
+
+        for _ in 0..<10_000 {
+            let t = loop.scheduleTask(in: .hours(1)) {}
+            scheduleds.append(t)
+        }
+
+        for t in scheduleds {
+            t.cancel()
+        }
+    }
+}
 
 final class RepeatedRequests: ChannelInboundHandler {
     typealias InboundIn = HTTPClientResponsePart
diff --git a/IntegrationTests/tests_04_performance/test_01_resources/test_1000_autoReadGetAndSet_sync.swift b/IntegrationTests/tests_04_performance/test_01_resources/test_1000_autoReadGetAndSet_sync.swift
index 45aa4d6a5d..3cc075d7b5 100644
--- a/IntegrationTests/tests_04_performance/test_01_resources/test_1000_autoReadGetAndSet_sync.swift
+++ b/IntegrationTests/tests_04_performance/test_01_resources/test_1000_autoReadGetAndSet_sync.swift
@@ -16,6 +16,7 @@ import NIOCore
 import NIOPosix
 
 func run(identifier: String) {
+    let group = MultiThreadedEventLoopGroup.preheatedSingleton
     MultiThreadedEventLoopGroup.withCurrentThreadAsEventLoop { loop in
         ServerBootstrap(group: group).bind(host: "127.0.0.1", port: 0).map { server in
             measure(identifier: identifier) {
diff --git a/IntegrationTests/tests_04_performance/test_01_resources/test_1000_rst_connections.swift b/IntegrationTests/tests_04_performance/test_01_resources/test_1000_rst_connections.swift
index 3e8bf65af8..d0d60b7704 100644
--- a/IntegrationTests/tests_04_performance/test_01_resources/test_1000_rst_connections.swift
+++ b/IntegrationTests/tests_04_performance/test_01_resources/test_1000_rst_connections.swift
@@ -27,10 +27,7 @@ private final class CloseAfterTimeoutHandler: ChannelInboundHandler {
 }
 
 func run(identifier: String) {
-    let group = MultiThreadedEventLoopGroup(numberOfThreads: 1)
-    defer {
-        try! group.syncShutdownGracefully()
-    }
+    let group = MultiThreadedEventLoopGroup.preheatedSingleton.next()
 
     let serverConnection = try! ServerBootstrap(group: group)
         .bind(host: "localhost", port: 0)
diff --git a/IntegrationTests/tests_04_performance/test_01_resources/test_assume_isolated_scheduling_10000_executions.swift b/IntegrationTests/tests_04_performance/test_01_resources/test_assume_isolated_scheduling_10000_executions.swift
index 7087e17aa7..41df0a1559 100644
--- a/IntegrationTests/tests_04_performance/test_01_resources/test_assume_isolated_scheduling_10000_executions.swift
+++ b/IntegrationTests/tests_04_performance/test_01_resources/test_assume_isolated_scheduling_10000_executions.swift
@@ -17,7 +17,7 @@ import NIOPosix
 
 func run(identifier: String) {
     measure(identifier: identifier) {
-        let group = MultiThreadedEventLoopGroup(numberOfThreads: 1)
+        let group = MultiThreadedEventLoopGroup.preheatedSingleton.next()
         let loop = group.next()
         let dg = DispatchGroup()
 
@@ -28,7 +28,6 @@ func run(identifier: String) {
             }
         }.wait()
         dg.wait()
-        try! group.syncShutdownGracefully()
         return 10_000
     }
 }
diff --git a/IntegrationTests/tests_04_performance/test_01_resources/test_flat_schedule_10000_tasks.swift b/IntegrationTests/tests_04_performance/test_01_resources/test_flat_schedule_10000_tasks.swift
index 1d80f8d43f..7098474724 100644
--- a/IntegrationTests/tests_04_performance/test_01_resources/test_flat_schedule_10000_tasks.swift
+++ b/IntegrationTests/tests_04_performance/test_01_resources/test_flat_schedule_10000_tasks.swift
@@ -18,24 +18,32 @@ import NIOPosix
 
 func run(identifier: String) {
     measure(identifier: identifier) {
-        let group = MultiThreadedEventLoopGroup(numberOfThreads: 1)
+        let group = MultiThreadedEventLoopGroup.preheatedSingleton
         let loop = group.next()
-        let counter = try! loop.submit { () -> Int in
+        let (counter, tasks) = try! loop.submit { () -> (Int, [Scheduled<Int>]) in
+            let iterations = 10_000
+
             var counter: Int = 0
+            var tasks: [Scheduled<Int>] = []
+            tasks.reserveCapacity(iterations)
 
             let deadline = NIODeadline.now() + .hours(1)
 
-            for _ in 0..<10000 {
-                loop.flatScheduleTask(deadline: deadline) {
+            for _ in 0..<iterations {
+                let task = loop.flatScheduleTask(deadline: deadline) {
                     counter &+= 1
                     return loop.makeSucceededFuture(counter)
                 }
+                tasks.append(task)
             }
 
-            return counter
+            return (counter, tasks)
         }.wait()
 
-        try! group.syncShutdownGracefully()
+        for task in tasks {
+            task.cancel()
+        }
+
         return counter
     }
 }
diff --git a/IntegrationTests/tests_04_performance/test_01_resources/test_flat_schedule_assume_isolated_10000_tasks.swift b/IntegrationTests/tests_04_performance/test_01_resources/test_flat_schedule_assume_isolated_10000_tasks.swift
index 4f980a00b0..7b6c076e6a 100644
--- a/IntegrationTests/tests_04_performance/test_01_resources/test_flat_schedule_assume_isolated_10000_tasks.swift
+++ b/IntegrationTests/tests_04_performance/test_01_resources/test_flat_schedule_assume_isolated_10000_tasks.swift
@@ -18,24 +18,32 @@ import NIOPosix
 
 func run(identifier: String) {
     measure(identifier: identifier) {
-        let group = MultiThreadedEventLoopGroup(numberOfThreads: 1)
+        let group = MultiThreadedEventLoopGroup.preheatedSingleton
         let loop = group.next()
-        let counter = try! loop.submit { () -> Int in
+        let (counter, tasks) = try! loop.submit { () -> (Int, [Scheduled<Int>]) in
+            let iterations = 10_000
+
             var counter: Int = 0
+            var tasks: [Scheduled<Int>] = []
+            tasks.reserveCapacity(iterations)
 
             let deadline = NIODeadline.now() + .hours(1)
 
-            for _ in 0..<10000 {
-                loop.assumeIsolated().flatScheduleTask(deadline: deadline) {
+            for _ in 0..<iterations {
+                let task = loop.assumeIsolated().flatScheduleTask(deadline: deadline) {
                     counter &+= 1
                     return loop.makeSucceededFuture(counter)
                 }
+                tasks.append(task)
             }
 
-            return counter
+            return (counter, tasks)
         }.wait()
 
-        try! group.syncShutdownGracefully()
+        for task in tasks {
+            task.cancel()
+        }
+
         return counter
     }
 }
diff --git a/IntegrationTests/tests_04_performance/test_01_resources/test_schedule_10000_tasks.swift b/IntegrationTests/tests_04_performance/test_01_resources/test_schedule_10000_tasks.swift
index 6dfd8de24e..025265b5e6 100644
--- a/IntegrationTests/tests_04_performance/test_01_resources/test_schedule_10000_tasks.swift
+++ b/IntegrationTests/tests_04_performance/test_01_resources/test_schedule_10000_tasks.swift
@@ -13,25 +13,33 @@
 //===----------------------------------------------------------------------===//
 
 import Dispatch
+import NIOCore
 import NIOPosix
 
 func run(identifier: String) {
     measure(identifier: identifier) {
-        let group = MultiThreadedEventLoopGroup(numberOfThreads: 1)
+        let group = MultiThreadedEventLoopGroup.preheatedSingleton
         let loop = group.next()
-        let counter = try! loop.submit { () -> Int in
+        let (counter, tasks) = try! loop.submit { () -> (Int, [Scheduled<Void>]) in
+            let iterations = 10_000
             var counter: Int = 0
+            var tasks = [Scheduled<Void>]()
+            tasks.reserveCapacity(iterations)
 
-            for _ in 0..<10000 {
-                loop.scheduleTask(in: .hours(1)) {
+            for _ in 0..<iterations {
+                let task = loop.scheduleTask(in: .hours(1)) {
                     counter &+= 1
                 }
+                tasks.append(task)
             }
 
-            return counter
+            return (counter, tasks)
         }.wait()
 
-        try! group.syncShutdownGracefully()
+        for task in tasks {
+            task.cancel()
+        }
+
         return counter
     }
 }
diff --git a/IntegrationTests/tests_04_performance/test_01_resources/test_schedule_and_run_10000_tasks.swift b/IntegrationTests/tests_04_performance/test_01_resources/test_schedule_and_run_10000_tasks.swift
index 8d70991b17..30b2d07640 100644
--- a/IntegrationTests/tests_04_performance/test_01_resources/test_schedule_and_run_10000_tasks.swift
+++ b/IntegrationTests/tests_04_performance/test_01_resources/test_schedule_and_run_10000_tasks.swift
@@ -13,10 +13,11 @@
 //===----------------------------------------------------------------------===//
 
 import Dispatch
+import NIOCore
 import NIOPosix
 
 func run(identifier: String) {
-    let group = MultiThreadedEventLoopGroup(numberOfThreads: 1)
+    let group = MultiThreadedEventLoopGroup.preheatedSingleton
     let loop = group.next()
     let dg = DispatchGroup()
 
@@ -37,6 +38,4 @@ func run(identifier: String) {
 
         return counter
     }
-
-    try! group.syncShutdownGracefully()
 }
diff --git a/IntegrationTests/tests_04_performance/test_01_resources/test_schedule_assume_isolated_10000_tasks.swift b/IntegrationTests/tests_04_performance/test_01_resources/test_schedule_assume_isolated_10000_tasks.swift
index 7d63b19fbc..e993ea55ee 100644
--- a/IntegrationTests/tests_04_performance/test_01_resources/test_schedule_assume_isolated_10000_tasks.swift
+++ b/IntegrationTests/tests_04_performance/test_01_resources/test_schedule_assume_isolated_10000_tasks.swift
@@ -13,25 +13,33 @@
 //===----------------------------------------------------------------------===//
 
 import Dispatch
+import NIOCore
 import NIOPosix
 
 func run(identifier: String) {
     measure(identifier: identifier) {
-        let group = MultiThreadedEventLoopGroup(numberOfThreads: 1)
+        let group = MultiThreadedEventLoopGroup.preheatedSingleton
         let loop = group.next()
-        let counter = try! loop.submit { () -> Int in
+        let (counter, tasks) = try! loop.submit { () -> (Int, [Scheduled<Void>]) in
+            let iterations = 10_000
             var counter: Int = 0
+            var tasks = [Scheduled<Void>]()
+            tasks.reserveCapacity(iterations)
 
-            for _ in 0..<10000 {
-                loop.assumeIsolated().scheduleTask(in: .hours(1)) {
+            for _ in 0..<iterations {
+                let task = loop.assumeIsolated().scheduleTask(in: .hours(1)) {
                     counter &+= 1
                 }
+                tasks.append(task)
             }
 
-            return counter
+            return (counter, tasks)
         }.wait()
 
-        try! group.syncShutdownGracefully()
+        for task in tasks {
+            task.cancel()
+        }
+
         return counter
     }
 }
diff --git a/IntegrationTests/tests_04_performance/test_01_resources/test_schedule_with_deadline_10000_tasks.swift b/IntegrationTests/tests_04_performance/test_01_resources/test_schedule_with_deadline_10000_tasks.swift
index 8b10c78eb6..9bea15bdaf 100644
--- a/IntegrationTests/tests_04_performance/test_01_resources/test_schedule_with_deadline_10000_tasks.swift
+++ b/IntegrationTests/tests_04_performance/test_01_resources/test_schedule_with_deadline_10000_tasks.swift
@@ -18,23 +18,31 @@ import NIOPosix
 
 func run(identifier: String) {
     measure(identifier: identifier) {
-        let group = MultiThreadedEventLoopGroup(numberOfThreads: 1)
+        let group = MultiThreadedEventLoopGroup.preheatedSingleton
         let loop = group.next()
-        let counter = try! loop.submit { () -> Int in
+        let (counter, tasks) = try! loop.submit { () -> (Int, [Scheduled<Void>]) in
+            let iterations = 10_000
             var counter: Int = 0
 
+            var tasks = [Scheduled<Void>]()
+            tasks.reserveCapacity(iterations)
+
             let deadline = NIODeadline.now() + .hours(1)
 
-            for _ in 0..<10000 {
-                loop.scheduleTask(deadline: deadline) {
+            for _ in 0..<iterations {
+                let task = loop.scheduleTask(deadline: deadline) {
                     counter &+= 1
                 }
+                tasks.append(task)
             }
 
-            return counter
+            return (counter, tasks)
         }.wait()
 
-        try! group.syncShutdownGracefully()
+        for task in tasks {
+            task.cancel()
+        }
+
         return counter
     }
 }
diff --git a/IntegrationTests/tests_04_performance/test_01_resources/test_schedule_with_deadline_assume_isolated_10000_tasks.swift b/IntegrationTests/tests_04_performance/test_01_resources/test_schedule_with_deadline_assume_isolated_10000_tasks.swift
index b0e157b0c9..bcae21551a 100644
--- a/IntegrationTests/tests_04_performance/test_01_resources/test_schedule_with_deadline_assume_isolated_10000_tasks.swift
+++ b/IntegrationTests/tests_04_performance/test_01_resources/test_schedule_with_deadline_assume_isolated_10000_tasks.swift
@@ -18,24 +18,31 @@ import NIOPosix
 
 func run(identifier: String) {
     measure(identifier: identifier) {
-        let group = MultiThreadedEventLoopGroup(numberOfThreads: 1)
+        let group = MultiThreadedEventLoopGroup.preheatedSingleton
         let loop = group.next()
-        let counter = try! loop.submit { () -> Int in
+        let (counter, tasks) = try! loop.submit { () -> (Int, [Scheduled<Int>]) in
+            let iterations = 10_000
             var counter: Int = 0
+            var tasks = [Scheduled<Int>]()
+            tasks.reserveCapacity(iterations)
 
             let deadline = NIODeadline.now() + .hours(1)
 
-            for _ in 0..<10000 {
-                loop.assumeIsolated().scheduleTask(deadline: deadline) {
+            for _ in 0..<iterations {
+                let task = loop.assumeIsolated().scheduleTask(deadline: deadline) {
                     counter &+= 1
                     return counter
                 }
+                tasks.append(task)
             }
 
-            return counter
+            return (counter, tasks)
         }.wait()
 
-        try! group.syncShutdownGracefully()
+        for task in tasks {
+            task.cancel()
+        }
+
         return counter
     }
 }
diff --git a/IntegrationTests/tests_04_performance/test_01_resources/test_scheduling_10000_executions.swift b/IntegrationTests/tests_04_performance/test_01_resources/test_scheduling_10000_executions.swift
index cf42e2e37b..faf890c9b0 100644
--- a/IntegrationTests/tests_04_performance/test_01_resources/test_scheduling_10000_executions.swift
+++ b/IntegrationTests/tests_04_performance/test_01_resources/test_scheduling_10000_executions.swift
@@ -17,7 +17,7 @@ import NIOPosix
 
 func run(identifier: String) {
     measure(identifier: identifier) {
-        let group = MultiThreadedEventLoopGroup(numberOfThreads: 1)
+        let group = MultiThreadedEventLoopGroup.preheatedSingleton
         let loop = group.next()
         let dg = DispatchGroup()
 
@@ -28,7 +28,6 @@ func run(identifier: String) {
             }
         }.wait()
         dg.wait()
-        try! group.syncShutdownGracefully()
         return 10_000
     }
 }
diff --git a/IntegrationTests/tests_04_performance/test_01_resources/test_submit_10000_tasks.swift b/IntegrationTests/tests_04_performance/test_01_resources/test_submit_10000_tasks.swift
index 88ae885422..2be4028695 100644
--- a/IntegrationTests/tests_04_performance/test_01_resources/test_submit_10000_tasks.swift
+++ b/IntegrationTests/tests_04_performance/test_01_resources/test_submit_10000_tasks.swift
@@ -17,7 +17,7 @@ import NIOPosix
 
 func run(identifier: String) {
     measure(identifier: identifier) {
-        let group = MultiThreadedEventLoopGroup(numberOfThreads: 1)
+        let group = MultiThreadedEventLoopGroup.preheatedSingleton
         let loop = group.next()
         let counter = try! loop.submit { () -> Int in
             var counter: Int = 0
@@ -32,7 +32,6 @@ func run(identifier: String) {
             return counter
         }.wait()
 
-        try! group.syncShutdownGracefully()
         return counter
     }
 }
diff --git a/IntegrationTests/tests_04_performance/test_01_resources/test_submit_assume_isolated_10000_tasks.swift b/IntegrationTests/tests_04_performance/test_01_resources/test_submit_assume_isolated_10000_tasks.swift
index 47f16587ab..a5fbcb69d0 100644
--- a/IntegrationTests/tests_04_performance/test_01_resources/test_submit_assume_isolated_10000_tasks.swift
+++ b/IntegrationTests/tests_04_performance/test_01_resources/test_submit_assume_isolated_10000_tasks.swift
@@ -17,7 +17,7 @@ import NIOPosix
 
 func run(identifier: String) {
     measure(identifier: identifier) {
-        let group = MultiThreadedEventLoopGroup(numberOfThreads: 1)
+        let group = MultiThreadedEventLoopGroup.preheatedSingleton
         let loop = group.next()
         let counter = try! loop.submit { () -> Int in
             var counter: Int = 0
@@ -32,7 +32,6 @@ func run(identifier: String) {
             return counter
         }.wait()
 
-        try! group.syncShutdownGracefully()
         return counter
     }
 }