diff --git a/include/chia/phase1.hpp b/include/chia/phase1.hpp
index 7813bb56..8d282411 100644
--- a/include/chia/phase1.hpp
+++ b/include/chia/phase1.hpp
@@ -381,7 +381,7 @@ uint64_t compute_matches(	int R_index, int num_threads,
 			}
 		}, "phase1/slice");
 	
-	L_sort->read(&read_thread, std::max(num_threads / 2, 2));
+	L_sort->read(&read_thread, std::max(num_threads / 2, 2), std::max(num_threads / g_read_thread_divider, 2));
 	
 	read_thread.close();
 	match_pool.close();
diff --git a/include/chia/phase2.hpp b/include/chia/phase2.hpp
index 3c71e21e..c915ddf5 100644
--- a/include/chia/phase2.hpp
+++ b/include/chia/phase2.hpp
@@ -24,7 +24,7 @@ void compute_table(	int R_index, int num_threads,
 					bitfield* L_used,
 					const bitfield* R_used)
 {
-	const int num_threads_read = std::max(num_threads / 4, 2);
+	const int num_threads_read = std::max(num_threads / g_read_thread_divider, 1);
 	
 	DiskTable<T> R_input(R_table);
 	{
diff --git a/include/chia/phase3.hpp b/include/chia/phase3.hpp
index e0e268fe..bc4d9c4f 100644
--- a/include/chia/phase3.hpp
+++ b/include/chia/phase3.hpp
@@ -25,7 +25,8 @@ void compute_stage1(int L_index, int num_threads,
 					DiskTable<S>* R_table = nullptr)
 {
 	const auto begin = get_wall_time_micros();
-	const int num_threads_merge = std::max(num_threads / 4, 1);
+	const int num_threads_read = std::max(num_threads / g_read_thread_divider, 2);
+	const int num_threads_merge = std::max(num_threads / 8, 1);
 	
 	struct merge_buffer_t {
 		uint64_t offset = 0;					// position offset at buffer[0]
@@ -164,11 +165,11 @@ void compute_stage1(int L_index, int num_threads,
 		}, &R_add_2, num_threads_merge, "phase3/merge");
 	
 	std::thread R_sort_read(
-		[&mutex, &signal_1, num_threads, L_table, R_sort, R_table, &R_read, &R_is_end]() {
+		[&mutex, &signal_1, num_threads, num_threads_read, L_table, R_sort, R_table, &R_read, &R_is_end]() {
 			if(R_table) {
-				R_table->read(&R_read, std::max(num_threads / 4, 2));
+				R_table->read(&R_read, std::max(num_threads_read / 2, 1));
 			} else {
-				R_sort->read(&R_read, std::max(num_threads / (L_table ? 1 : 2), 1));
+				R_sort->read(&R_read, std::max(num_threads / (L_table ? 1 : 2), 1), std::max(num_threads_read / 2, 1));
 			}
 			R_read.close();
 			{
@@ -179,10 +180,10 @@ void compute_stage1(int L_index, int num_threads,
 		});
 	
 	if(L_table) {
-		L_table->read(&L_read_1, std::max(num_threads / 4, 2));
+		L_table->read(&L_read_1, std::max(num_threads_read / 2, 1));
 		L_read_1.close();
 	} else {
-		L_sort->read(&L_read, std::max(num_threads / (R_table ? 1 : 2), 1));
+		L_sort->read(&L_read, std::max(num_threads / (R_table ? 1 : 2), 1), std::max(num_threads_read / 2, 1));
 	}
 	L_read.close();
 	{
@@ -439,7 +440,7 @@ uint64_t compute_stage2(int L_index, int num_threads,
 			L_add.take(input);
 		}, "phase3/slice");
 	
-	R_sort->read(&R_read, num_threads);
+	R_sort->read(&R_read, num_threads, std::max(num_threads / g_read_thread_divider, 2));
 	R_read.close();
 	
 	// Since we don't have a perfect multiple of EPP entries, this writes the last ones
diff --git a/include/chia/phase4.hpp b/include/chia/phase4.hpp
index 036e4452..7c971287 100644
--- a/include/chia/phase4.hpp
+++ b/include/chia/phase4.hpp
@@ -190,7 +190,7 @@ uint64_t compute(	FILE* plot_file, const int header_size,
 		p7_threads.take(parks);
 	}, "phase4/read");
     
-    L_sort_7->read(&read_thread, num_threads);
+    L_sort_7->read(&read_thread, num_threads, std::max(num_threads / g_read_thread_divider, 2));
     read_thread.close();
     
     park_data.offset = final_file_writer_3;
diff --git a/include/chia/settings.h b/include/chia/settings.h
index d9e29783..9482634c 100644
--- a/include/chia/settings.h
+++ b/include/chia/settings.h
@@ -24,6 +24,12 @@ extern size_t g_read_chunk_size;
  */
 extern size_t g_write_chunk_size;
 
+/*
+ * Divider for number of read threads.
+ * default = 4
+ */
+extern int g_read_thread_divider;
+
 namespace phase2 {
   extern int g_thread_multi;
 }
diff --git a/src/chia_plot.cpp b/src/chia_plot.cpp
index dc031f52..e0d46a8c 100644
--- a/src/chia_plot.cpp
+++ b/src/chia_plot.cpp
@@ -246,6 +246,7 @@ int main(int argc, char** argv)
 		"f, farmerkey", "Farmer Public Key (48 bytes)", cxxopts::value<std::string>(farmer_key_str))(
 		"G, tmptoggle", "Alternate tmpdir/tmpdir2", cxxopts::value<bool>(tmptoggle))(
 		"K, rmulti2", "Thread multiplier for P2 (default = 1)", cxxopts::value<int>(phase2::g_thread_multi))(
+		"R, rtdiv", "Number of read threads divider (default = 4)", cxxopts::value<int>(g_read_thread_divider))(
 		"help", "Print help");
 	
 	if(argc <= 1) {
diff --git a/src/settings.cpp b/src/settings.cpp
index ee85b7d5..d60cf1a4 100644
--- a/src/settings.cpp
+++ b/src/settings.cpp
@@ -11,6 +11,8 @@
 size_t g_read_chunk_size = 65536;
 size_t g_write_chunk_size = 4096;
 
+int g_read_thread_divider = 4;
+
 namespace phase2 {
   int g_thread_multi = 1;
 }