--- a/jdk/src/share/classes/com/sun/imageio/plugins/png/PNGMetadata.java	Mon Jun 16 08:09:30 2014 -0700
+++ b/jdk/src/share/classes/com/sun/imageio/plugins/png/PNGMetadata.java	Mon Jun 16 17:45:26 2014 +0100
@@ -900,7 +900,7 @@
         if (times == 1) {
             return s;
         }
-        StringBuffer sb = new StringBuffer((s.length() + 1)*times - 1);
+        StringBuilder sb = new StringBuilder((s.length() + 1)*times - 1);
         sb.append(s);
         for (int i = 1; i < times; i++) {
             sb.append(" ");