diff --git a/src/Build/Logging/BinaryLogger/BuildEventArgsWriter.cs b/src/Build/Logging/BinaryLogger/BuildEventArgsWriter.cs
index 568832ce500..8c1ba1abaed 100644
--- a/src/Build/Logging/BinaryLogger/BuildEventArgsWriter.cs
+++ b/src/Build/Logging/BinaryLogger/BuildEventArgsWriter.cs
@@ -103,6 +103,9 @@ internal class BuildEventArgsWriter
         public BuildEventArgsWriter(BinaryWriter binaryWriter)
         {
             this.originalStream = binaryWriter.BaseStream;
+
+            // this doesn't exceed 30K for smaller binlogs so seems like a reasonable
+            // starting point to avoid reallocations in the common case
             this.currentRecordStream = new MemoryStream(65536);
 
             this.originalBinaryWriter = binaryWriter;