Based on feedback from another professional game company, there are several improvements, including some API change...

Some dynamic memory allocations have been replace by pool allocation or stack allocations.
quantized aabb versus quantized aabb overlap check is made branch-free (helps a lot on consoles PS3/XBox 360)
Collision algorithms are now created through a new btDefaultCollisionConfiguration, to decouple dependency (this is the API change):
Example:
	btDefaultCollisionConfiguration* collisionConfiguration = new btDefaultCollisionConfiguration();
	m_dispatcher = new	btCollisionDispatcher(collisionConfiguration);

src/BulletCollision/CollisionDispatch/btCollisionDispatcher.h

@@ -26,7 +26,8 @@ subject to the following restrictions:
 
 class btIDebugDraw;
 class btOverlappingPairCache;
-
+class btPoolAllocator;
+class btCollisionConfiguration;
 
 #include "btCollisionCreateFunc.h"
 
@@ -51,21 +52,15 @@ class btCollisionDispatcher : public btDispatcher
 
 	btNearCallback		m_nearCallback;
 	
+	btPoolAllocator*	m_collisionAlgorithmPoolAllocator;
+
+	btPoolAllocator*	m_persistentManifoldPoolAllocator;
+
 	btCollisionAlgorithmCreateFunc* m_doubleDispatch[MAX_BROADPHASE_COLLISION_TYPES][MAX_BROADPHASE_COLLISION_TYPES];
 	
-	btCollisionAlgorithmCreateFunc* internalFindCreateFunc(int proxyType0,int proxyType1);
 
-	//default CreationFunctions, filling the m_doubleDispatch table
-	btCollisionAlgorithmCreateFunc*	m_convexConvexCreateFunc;
-	btCollisionAlgorithmCreateFunc*	m_convexConcaveCreateFunc;
-	btCollisionAlgorithmCreateFunc*	m_swappedConvexConcaveCreateFunc;
-	btCollisionAlgorithmCreateFunc*	m_compoundCreateFunc;
-	btCollisionAlgorithmCreateFunc*	m_swappedCompoundCreateFunc;
-	btCollisionAlgorithmCreateFunc*   m_emptyCreateFunc;
+	btCollisionConfiguration*	m_collisionConfiguration;
 
-#ifndef USE_DISPATCH_REGISTRY_ARRAY
-	btCollisionAlgorithm* internalFindAlgorithm(btCollisionObject* body0,btCollisionObject* body1,btPersistentManifold* sharedManifold = 0);
-#endif //USE_DISPATCH_REGISTRY_ARRAY
 
 public:
 
@@ -92,11 +87,7 @@ public:
 		return m_manifoldsPtr[index];
 	}
 
-	///the default constructor creates/register default collision algorithms, for convex, compound and concave shape support
-	btCollisionDispatcher ();
-
-	///a special constructor that doesn't create/register the default collision algorithms
-	btCollisionDispatcher(bool noDefaultAlgorithms);
+	btCollisionDispatcher (btCollisionConfiguration* collisionConfiguration);
 
 	virtual ~btCollisionDispatcher();
 
@@ -114,7 +105,7 @@ public:
 	
 	virtual bool	needsResponse(btCollisionObject* body0,btCollisionObject* body1);
 	
-	virtual void	dispatchAllCollisionPairs(btOverlappingPairCache* pairCache,btDispatcherInfo& dispatchInfo);
+	virtual void	dispatchAllCollisionPairs(btOverlappingPairCache* pairCache,btDispatcherInfo& dispatchInfo,btDispatcher* dispatcher);
 
 	void	setNearCallback(btNearCallback	nearCallback)
 	{
@@ -129,6 +120,11 @@ public:
 	//by default, Bullet will use this near callback
 	static void  defaultNearCallback(btBroadphasePair& collisionPair, btCollisionDispatcher& dispatcher, btDispatcherInfo& dispatchInfo);
 
+	virtual	void* allocateCollisionAlgorithm(int size);
+
+	virtual	void freeCollisionAlgorithm(void* ptr);
+
+
 };
 
 #endif //COLLISION__DISPATCHER_H