diff --git a/querydsl-core/src/main/java/com/mysema/query/JoinExpression.java b/querydsl-core/src/main/java/com/mysema/query/JoinExpression.java
index 0afc2f5d6..7d4381db3 100644
--- a/querydsl-core/src/main/java/com/mysema/query/JoinExpression.java
+++ b/querydsl-core/src/main/java/com/mysema/query/JoinExpression.java
@@ -35,7 +35,7 @@ public final class JoinExpression implements Serializable {
     @Nullable
     private final Predicate condition;
 
-    private final Set<JoinFlag> flags;
+    private final ImmutableSet<JoinFlag> flags;
 
     private final Expression<?> target;
 
@@ -65,7 +65,7 @@ public final class JoinExpression implements Serializable {
         this.type = type;
         this.target = target;
         this.condition = condition;
-        this.flags = flags;
+        this.flags = ImmutableSet.copyOf(flags);
     }
 
     @Nullable
diff --git a/querydsl-core/src/main/java/com/mysema/query/SearchResults.java b/querydsl-core/src/main/java/com/mysema/query/SearchResults.java
index a6a782982..a7810d518 100644
--- a/querydsl-core/src/main/java/com/mysema/query/SearchResults.java
+++ b/querydsl-core/src/main/java/com/mysema/query/SearchResults.java
@@ -26,9 +26,10 @@ import com.google.common.collect.ImmutableList;
  */
 public final class SearchResults<T> {
 
-    private static final SearchResults EMPTY = new SearchResults(
+    private static final SearchResults<Object> EMPTY = new SearchResults<Object>(
             ImmutableList.of(), Long.MAX_VALUE, 0l, 0l); 
     
+    @SuppressWarnings("unchecked")
     public static <T> SearchResults<T> emptyResults() {
         return (SearchResults<T>)EMPTY;
     };
diff --git a/querydsl-core/src/main/java/com/mysema/query/SimpleProjectable.java b/querydsl-core/src/main/java/com/mysema/query/SimpleProjectable.java
index cc87e46d4..8fe552518 100644
--- a/querydsl-core/src/main/java/com/mysema/query/SimpleProjectable.java
+++ b/querydsl-core/src/main/java/com/mysema/query/SimpleProjectable.java
@@ -49,6 +49,7 @@ public interface SimpleProjectable<T> {
      *
      * @return
      */
+    @Deprecated
     CloseableIterator<T> iterateDistinct();
 
     /**
@@ -63,6 +64,7 @@ public interface SimpleProjectable<T> {
      *
      * @return
      */
+    @Deprecated
     List<T> listDistinct();
 
     /**
@@ -96,6 +98,7 @@ public interface SimpleProjectable<T> {
      *
      * @return
      */
+    @Deprecated
     SearchResults<T> listDistinctResults();
 
     /**
@@ -110,6 +113,7 @@ public interface SimpleProjectable<T> {
      *
      * @return
      */
+    @Deprecated
     long countDistinct();
 
 }
diff --git a/querydsl-core/src/main/java/com/mysema/query/support/SerializerBase.java b/querydsl-core/src/main/java/com/mysema/query/support/SerializerBase.java
index 814380a21..c62e55f80 100644
--- a/querydsl-core/src/main/java/com/mysema/query/support/SerializerBase.java
+++ b/querydsl-core/src/main/java/com/mysema/query/support/SerializerBase.java
@@ -49,7 +49,7 @@ public abstract class SerializerBase<S extends SerializerBase<S>> implements Vis
 
     private String anonParamPrefix = "_";
 
-    private final Map<Object,String> constantToLabel = new HashMap<Object,String>(4);
+    private Map<Object,String> constantToLabel;
 
     @SuppressWarnings("unchecked")
     private final S self = (S) this;
@@ -82,6 +82,9 @@ public abstract class SerializerBase<S extends SerializerBase<S>> implements Vis
     }
 
     public Map<Object,String> getConstantToLabel() {
+        if (constantToLabel == null) {
+            constantToLabel = new HashMap<Object,String>(4);   
+        }
         return constantToLabel;
     }
     
diff --git a/querydsl-core/src/main/java/com/mysema/query/types/OperatorImpl.java b/querydsl-core/src/main/java/com/mysema/query/types/OperatorImpl.java
index dd5f89250..722d318a8 100644
--- a/querydsl-core/src/main/java/com/mysema/query/types/OperatorImpl.java
+++ b/querydsl-core/src/main/java/com/mysema/query/types/OperatorImpl.java
@@ -33,7 +33,7 @@ public final class OperatorImpl<T> implements Operator<T> {
     }
 
     public OperatorImpl(String id, ImmutableList<Class<?>> types) {
-        this.id = id.intern();
+        this.id = id;
         this.types = types;
     }
 
@@ -52,8 +52,7 @@ public final class OperatorImpl<T> implements Operator<T> {
         if (o == this) {
             return true;
         } else if (o instanceof Operator<?>) {
-            // Strings are interned, so this is safe
-            return ((Operator<?>)o).getId() == id;
+            return ((Operator<?>)o).getId().equals(id);
         } else {
             return false;
         }
diff --git a/querydsl-core/src/main/java/com/mysema/query/types/PathType.java b/querydsl-core/src/main/java/com/mysema/query/types/PathType.java
index 1fc64bf06..970aff2ed 100644
--- a/querydsl-core/src/main/java/com/mysema/query/types/PathType.java
+++ b/querydsl-core/src/main/java/com/mysema/query/types/PathType.java
@@ -70,8 +70,6 @@ public enum PathType implements Operator<Path<?>> {
      */
     VARIABLE;
 
-    private final String id = name().intern();
-    
     @Override
     public List<Class<?>> getTypes() {
         return Collections.emptyList();
@@ -79,7 +77,7 @@ public enum PathType implements Operator<Path<?>> {
 
     @Override
     public String getId() {
-        return id;
+        return name();
     }
     
 }
diff --git a/querydsl-core/src/main/java/com/mysema/query/types/QTuple.java b/querydsl-core/src/main/java/com/mysema/query/types/QTuple.java
index 948653829..74ac5afaf 100644
--- a/querydsl-core/src/main/java/com/mysema/query/types/QTuple.java
+++ b/querydsl-core/src/main/java/com/mysema/query/types/QTuple.java
@@ -120,8 +120,8 @@ public class QTuple extends ExpressionBase<Tuple> implements FactoryExpression<T
     public QTuple(Expression<?>[]... args) {
         super(Tuple.class);
         ImmutableList.Builder<Expression<?>> builder = ImmutableList.builder();
-        for (Expression<?>[] exprs: args){
-            builder.addAll(Arrays.asList(exprs));
+        for (Expression<?>[] exprs: args) {
+            builder.add(exprs);
         }
         this.args = builder.build();
     }
diff --git a/querydsl-core/src/main/java/com/mysema/query/types/Templates.java b/querydsl-core/src/main/java/com/mysema/query/types/Templates.java
index a6c3a813e..d5d425e0a 100644
--- a/querydsl-core/src/main/java/com/mysema/query/types/Templates.java
+++ b/querydsl-core/src/main/java/com/mysema/query/types/Templates.java
@@ -13,7 +13,7 @@
  */
 package com.mysema.query.types;
 
-import java.util.IdentityHashMap;
+import java.util.HashMap;
 import java.util.Map;
 
 import javax.annotation.Nullable;
@@ -27,9 +27,9 @@ public class Templates {
 
     public static final Templates DEFAULT = new Templates();
 
-    private final Map<String, Template> templates = new IdentityHashMap<String, Template>();
+    private final Map<String, Template> templates = new HashMap<String, Template>();
     
-    private final Map<String, Integer> precedence = new IdentityHashMap<String, Integer>();
+    private final Map<String, Integer> precedence = new HashMap<String, Integer>();
 
     private final TemplateFactory templateFactory;
     
diff --git a/querydsl-core/src/main/java/com/mysema/query/util/CollectionUtils.java b/querydsl-core/src/main/java/com/mysema/query/util/CollectionUtils.java
index 599376142..5886850a7 100644
--- a/querydsl-core/src/main/java/com/mysema/query/util/CollectionUtils.java
+++ b/querydsl-core/src/main/java/com/mysema/query/util/CollectionUtils.java
@@ -36,7 +36,7 @@ public final class CollectionUtils {
     public static <T> List<T> add(List<T> list, T element) {
         if (list.isEmpty()) {
             return ImmutableList.of(element);
-        } else if (list.size() == 1) {
+        } else if (list instanceof ImmutableList) {
             final List<T> old = list;
             list = Lists.newArrayList();
             list.add(old.get(0));
@@ -48,7 +48,7 @@ public final class CollectionUtils {
     public static <T> Set<T> add(Set<T> set, T element) {
         if (set.isEmpty()) {
             return ImmutableSet.of(element);
-        } else if (set.size() == 1) {
+        } else if (set instanceof ImmutableSet) {
             final Set<T> old = set;
             set = Sets.newHashSet();
             set.add(old.iterator().next());
@@ -60,7 +60,7 @@ public final class CollectionUtils {
     public static <T> Set<T> addSorted(Set<T> set, T element) {
         if (set.isEmpty()) {
             return ImmutableSet.of(element);
-        } else if (set.size() == 1) {
+        } else if (set instanceof ImmutableSet) {
             Set<T> old = set;
             set = Sets.newLinkedHashSet();
             set.add(old.iterator().next());
@@ -72,7 +72,7 @@ public final class CollectionUtils {
     public static <K,V> Map<K,V> put(Map<K,V> map, K key, V value) {
         if (map.isEmpty()) {
             return ImmutableMap.of(key, value);
-        } else if (map.size() == 1) {
+        } else if (map instanceof ImmutableMap) {
             map = Maps.newHashMap(map);
         }
         map.put(key, value);
diff --git a/querydsl-jpa/src/main/java/com/mysema/query/jpa/AbstractJPASubQuery.java b/querydsl-jpa/src/main/java/com/mysema/query/jpa/AbstractJPASubQuery.java
index 3541f0059..0f6d6430d 100644
--- a/querydsl-jpa/src/main/java/com/mysema/query/jpa/AbstractJPASubQuery.java
+++ b/querydsl-jpa/src/main/java/com/mysema/query/jpa/AbstractJPASubQuery.java
@@ -13,8 +13,6 @@
  */
 package com.mysema.query.jpa;
 
-import java.util.Collection;
-
 import com.mysema.query.DefaultQueryMetadata;
 import com.mysema.query.JoinExpression;
 import com.mysema.query.JoinType;
diff --git a/querydsl-jpa/src/main/java/com/mysema/query/jpa/JPACommonQuery.java b/querydsl-jpa/src/main/java/com/mysema/query/jpa/JPACommonQuery.java
index be05f5481..5f979d64e 100644
--- a/querydsl-jpa/src/main/java/com/mysema/query/jpa/JPACommonQuery.java
+++ b/querydsl-jpa/src/main/java/com/mysema/query/jpa/JPACommonQuery.java
@@ -13,8 +13,6 @@
  */
 package com.mysema.query.jpa;
 
-import java.util.Collection;
-
 import com.mysema.query.Query;
 import com.mysema.query.types.CollectionExpression;
 import com.mysema.query.types.EntityPath;
diff --git a/querydsl-jpa/src/main/java/com/mysema/query/jpa/JPAQueryMixin.java b/querydsl-jpa/src/main/java/com/mysema/query/jpa/JPAQueryMixin.java
index 1a8aa5892..62fe8250e 100644
--- a/querydsl-jpa/src/main/java/com/mysema/query/jpa/JPAQueryMixin.java
+++ b/querydsl-jpa/src/main/java/com/mysema/query/jpa/JPAQueryMixin.java
@@ -28,7 +28,6 @@ import com.mysema.query.types.ExpressionUtils;
 import com.mysema.query.types.Path;
 import com.mysema.query.types.Predicate;
 import com.mysema.query.types.TemplateExpressionImpl;
-import com.mysema.query.types.path.ListPath;
 
 /**
  * JPAQueryMixin extends {@link QueryMixin} to support JPQL join construction