diff --git a/release-notes/VERSION-2.x b/release-notes/VERSION-2.x
index 2a6251219c..c9f293fc64 100644
--- a/release-notes/VERSION-2.x
+++ b/release-notes/VERSION-2.x
@@ -14,6 +14,10 @@ JSON library.
 === Releases ===
 ------------------------------------------------------------------------
 
+(not yet released)
+
+#712: (partial) Optimize array allocation by JsonStringEncoder
+
 2.12.4 (06-Jul-2021)
 
 #702: `ArrayOutOfBoundException` at `WriterBasedJsonGenerator.writeString(Reader, int)`
diff --git a/src/main/java/com/fasterxml/jackson/core/io/JsonStringEncoder.java b/src/main/java/com/fasterxml/jackson/core/io/JsonStringEncoder.java
index a7a708c7bd..58d02a3da6 100644
--- a/src/main/java/com/fasterxml/jackson/core/io/JsonStringEncoder.java
+++ b/src/main/java/com/fasterxml/jackson/core/io/JsonStringEncoder.java
@@ -30,8 +30,9 @@ public final class JsonStringEncoder
     private final static int SURR2_FIRST = 0xDC00;
     private final static int SURR2_LAST = 0xDFFF;
 
-    private final static int INITIAL_CHAR_BUFFER_SIZE = 120;
-    private final static int INITIAL_BYTE_BUFFER_SIZE = 200;
+    // 18-Aug-2021, tatu: [core#712] use bit lower defaults for 2.11/2.12
+    private final static int INITIAL_CHAR_BUFFER_SIZE = 30;
+    private final static int INITIAL_BYTE_BUFFER_SIZE = 60;
 
     /*
     /**********************************************************************