diff --git a/src/main/java/com/google/gwtorm/client/CompoundKey.java b/src/main/java/com/google/gwtorm/client/CompoundKey.java
index 1c66d18..46a7b16 100644
--- a/src/main/java/com/google/gwtorm/client/CompoundKey.java
+++ b/src/main/java/com/google/gwtorm/client/CompoundKey.java
@@ -73,7 +73,7 @@
 
   @Override
   public String toString() {
-    final StringBuffer r = new StringBuffer();
+    final StringBuilder r = new StringBuilder();
     boolean first = true;
     if (getParentKey() != null) {
       r.append(KeyUtil.encode(getParentKey().toString()));
diff --git a/src/main/java/com/google/gwtorm/client/IntKey.java b/src/main/java/com/google/gwtorm/client/IntKey.java
index 08c90e0..266ab87 100644
--- a/src/main/java/com/google/gwtorm/client/IntKey.java
+++ b/src/main/java/com/google/gwtorm/client/IntKey.java
@@ -59,7 +59,7 @@
 
   @Override
   public String toString() {
-    final StringBuffer r = new StringBuffer();
+    final StringBuilder r = new StringBuilder();
     if (getParentKey() != null) {
       r.append(getParentKey().toString());
       r.append(',');
diff --git a/src/main/java/com/google/gwtorm/client/LongKey.java b/src/main/java/com/google/gwtorm/client/LongKey.java
index a983064..570f30a 100644
--- a/src/main/java/com/google/gwtorm/client/LongKey.java
+++ b/src/main/java/com/google/gwtorm/client/LongKey.java
@@ -59,7 +59,7 @@
 
   @Override
   public String toString() {
-    final StringBuffer r = new StringBuffer();
+    final StringBuilder r = new StringBuilder();
     if (getParentKey() != null) {
       r.append(getParentKey().toString());
       r.append(',');
diff --git a/src/main/java/com/google/gwtorm/client/ShortKey.java b/src/main/java/com/google/gwtorm/client/ShortKey.java
index efc7f57..2eecda9 100644
--- a/src/main/java/com/google/gwtorm/client/ShortKey.java
+++ b/src/main/java/com/google/gwtorm/client/ShortKey.java
@@ -59,7 +59,7 @@
 
   @Override
   public String toString() {
-    final StringBuffer r = new StringBuffer();
+    final StringBuilder r = new StringBuilder();
     if (getParentKey() != null) {
       r.append(getParentKey().toString());
       r.append(',');
diff --git a/src/main/java/com/google/gwtorm/client/StringKey.java b/src/main/java/com/google/gwtorm/client/StringKey.java
index e56661f..1a7f467 100644
--- a/src/main/java/com/google/gwtorm/client/StringKey.java
+++ b/src/main/java/com/google/gwtorm/client/StringKey.java
@@ -65,7 +65,7 @@
 
   @Override
   public String toString() {
-    final StringBuffer r = new StringBuffer();
+    final StringBuilder r = new StringBuilder();
     if (getParentKey() != null) {
       r.append(getParentKey().toString());
       r.append(',');
diff --git a/src/main/java/com/google/gwtorm/schema/SchemaModel.java b/src/main/java/com/google/gwtorm/schema/SchemaModel.java
index 3f188c1..6553f32 100644
--- a/src/main/java/com/google/gwtorm/schema/SchemaModel.java
+++ b/src/main/java/com/google/gwtorm/schema/SchemaModel.java
@@ -66,7 +66,7 @@
   }
 
   public String getCreateDatabaseSql(final SqlDialect dialect) {
-    final StringBuffer r = new StringBuffer();
+    final StringBuilder r = new StringBuilder();
 
     for (final SequenceModel seq : getSequences()) {
       r.append(seq.getCreateSequenceSql(dialect));
diff --git a/src/main/java/com/google/gwtorm/schema/sql/DialectDerby.java b/src/main/java/com/google/gwtorm/schema/sql/DialectDerby.java
index e8cd2ce..5314582 100644
--- a/src/main/java/com/google/gwtorm/schema/sql/DialectDerby.java
+++ b/src/main/java/com/google/gwtorm/schema/sql/DialectDerby.java
@@ -72,7 +72,7 @@
   public void renameColumn(
       StatementExecutor e, String tableName, String fromColumn, ColumnModel col)
       throws OrmException {
-    StringBuffer sb = new StringBuffer();
+    StringBuilder sb = new StringBuilder();
     sb.append("RENAME COLUMN ");
     sb.append(tableName);
     sb.append('.');
diff --git a/src/main/java/com/google/gwtorm/schema/sql/DialectMySQL.java b/src/main/java/com/google/gwtorm/schema/sql/DialectMySQL.java
index a233dce..c5a2028 100644
--- a/src/main/java/com/google/gwtorm/schema/sql/DialectMySQL.java
+++ b/src/main/java/com/google/gwtorm/schema/sql/DialectMySQL.java
@@ -209,7 +209,7 @@
   public void renameColumn(
       StatementExecutor stmt, String tableName, String fromColumn, ColumnModel col)
       throws OrmException {
-    StringBuffer r = new StringBuffer();
+    StringBuilder r = new StringBuilder();
     r.append("ALTER TABLE ");
     r.append(tableName);
     r.append(" CHANGE ");
diff --git a/src/main/java/com/google/gwtorm/schema/sql/DialectOracle.java b/src/main/java/com/google/gwtorm/schema/sql/DialectOracle.java
index bb44604..c975a17 100644
--- a/src/main/java/com/google/gwtorm/schema/sql/DialectOracle.java
+++ b/src/main/java/com/google/gwtorm/schema/sql/DialectOracle.java
@@ -126,7 +126,7 @@
   public void renameColumn(
       StatementExecutor e, String tableName, String fromColumn, ColumnModel col)
       throws OrmException {
-    StringBuffer sb = new StringBuffer();
+    StringBuilder sb = new StringBuilder();
     sb.append("ALTER TABLE ");
     sb.append(tableName);
     sb.append(" RENAME COLUMN ");