Custom allocator for weak_ptr

From high CPU usage in RtlpLowFragHeapAllocFromContext() I am making a guess that std::weak_ptr() that I use frequently (calling .lock() on it) should be the culprit that doesn't use the internal efficient memory pool, but rather resorts to malloc()/free()/new/delete guys.

Is there a way to specify custom allocator for an std::weak_ptr? If yes, how? If no, why?

UPDATE: uploading the profiler snapshot