diff --git a/CHANGELOG.md b/CHANGELOG.md
index 02d31643d69..9890893fe6f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -18,6 +18,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - `Logger.Enabled` in `go.opentelemetry.io/otel/log` now accepts a newly introduced `EnabledParameters` type instead of `Record`. (#5791)
 - `FilterProcessor.Enabled` in `go.opentelemetry.io/otel/sdk/log/internal/x` now accepts `EnabledParameters` instead of `Record`. (#5791)
 - The `Record` type in `go.opentelemetry.io/otel/log` is no longer comparable. (#5847)
+- Performance improvements for `recordingSpan` `SetAttributes`. (#5864)
 
 ### Deprecated
 
diff --git a/sdk/trace/span.go b/sdk/trace/span.go
index 2a993c12436..2ddd5518566 100644
--- a/sdk/trace/span.go
+++ b/sdk/trace/span.go
@@ -584,7 +584,7 @@ func (s *recordingSpan) Attributes() []attribute.KeyValue {
 func (s *recordingSpan) dedupeAttrs() {
 	// Do not set a capacity when creating this map. Benchmark testing has
 	// showed this to only add unused memory allocations in general use.
-	exists := make(map[attribute.Key]int)
+	exists := make(map[attribute.Key]int, len(s.attributes))
 	s.dedupeAttrsFromRecord(&exists)
 }