Index: org/apache/catalina/session/ManagerBase.java
===================================================================
--- org/apache/catalina/session/ManagerBase.java	(revision 831814)
+++ org/apache/catalina/session/ManagerBase.java	(working copy)
@@ -966,11 +966,11 @@
         String result = null;
 
         // Render the result as a String of hexadecimal digits
-        StringBuffer buffer = new StringBuffer();
+        StringBuilder buffer = new StringBuilder();
         do {
             int resultLenBytes = 0;
             if (result != null) {
-                buffer = new StringBuffer();
+                buffer = new StringBuilder();
                 duplicates++;
             }
 
@@ -1144,7 +1144,7 @@
      *
      */
     public String listSessionIds() {
-        StringBuffer sb=new StringBuffer();
+        StringBuilder sb=new StringBuilder();
         Iterator keys = sessions.keySet().iterator();
         while (keys.hasNext()) {
             sb.append(keys.next()).append(" ");
Index: org/apache/catalina/session/StandardSession.java
===================================================================
--- org/apache/catalina/session/StandardSession.java	(revision 831814)
+++ org/apache/catalina/session/StandardSession.java	(working copy)
@@ -901,7 +901,7 @@
      */
     public String toString() {
 
-        StringBuffer sb = new StringBuffer();
+        StringBuilder sb = new StringBuilder();
         sb.append("StandardSession[");
         sb.append(id);
         sb.append("]");