diff --git a/pkg/phlaredb/symdb/dedup_slice.go b/pkg/phlaredb/symdb/dedup_slice.go
index 78056f893e..f0f9face8f 100644
--- a/pkg/phlaredb/symdb/dedup_slice.go
+++ b/pkg/phlaredb/symdb/dedup_slice.go
@@ -254,7 +254,7 @@ func (s *deduplicatingSlice[M, K, H]) Size() uint64 {
 
 func (s *deduplicatingSlice[M, K, H]) ingest(elems []M, rewriter *rewriter) {
 	var (
-		rewritingMap = make(map[int64]int64)
+		rewritingMap = make(map[int64]int64, len(elems))
 		missing      = int64SlicePool.Get()
 	)
 	missing = missing[:0]
@@ -279,6 +279,7 @@ func (s *deduplicatingSlice[M, K, H]) ingest(elems []M, rewriter *rewriter) {
 	if len(missing) > 0 {
 		s.lock.Lock()
 		posSlice := int64(len(s.slice))
+		misSlice := make([]M, 0, len(missing))
 		for _, pos := range missing {
 			// check again if element exists
 			k := s.helper.key(elems[pos])
@@ -288,12 +289,13 @@ func (s *deduplicatingSlice[M, K, H]) ingest(elems []M, rewriter *rewriter) {
 			}
 
 			// add element to slice/map
-			s.slice = append(s.slice, s.helper.clone(elems[pos]))
+			misSlice = append(misSlice, s.helper.clone(elems[pos]))
 			s.lookup[k] = posSlice
 			rewritingMap[int64(s.helper.setID(uint64(pos), uint64(posSlice), &elems[pos]))] = posSlice
 			posSlice++
 			s.size.Add(s.helper.size(elems[pos]))
 		}
+		s.slice = append(s.slice, misSlice...)
 		s.lock.Unlock()
 	}
 
diff --git a/pkg/phlaredb/symdb/symdb_test.go b/pkg/phlaredb/symdb/symdb_test.go
index 2f8804081d..d804b28fd6 100644
--- a/pkg/phlaredb/symdb/symdb_test.go
+++ b/pkg/phlaredb/symdb/symdb_test.go
@@ -227,3 +227,23 @@ func TestWritePartition(t *testing.T) {
 `
 	require.Equal(t, expected, resolved.String())
 }
+
+func BenchmarkPartitionWriter_WriteProfileSymbols(b *testing.B) {
+	b.ReportAllocs()
+
+	p, err := pprof.OpenFile("testdata/profile.pb.gz")
+	require.NoError(b, err)
+	p.Normalize()
+	cfg := DefaultConfig().WithDirectory(b.TempDir())
+
+	db := NewSymDB(cfg)
+
+	for i := 0; i < b.N; i++ {
+		b.StopTimer()
+		newP := p.CloneVT()
+		pw := db.PartitionWriter(uint64(i))
+		b.StartTimer()
+
+		pw.WriteProfileSymbols(newP)
+	}
+}