Not completely sure if it's worth having for 8.0, but opening this to share the target I'm trying to reach.
-- v5: ntdll: Add a thread-specific category group cache. ntdll: Use atomics and lock-free list for category groups. ntdll: Implement Low Fragmentation Heap frontend. ntdll: Count allocations and automatically enable LFH. ntdll: Implement HeapCompatibilityInformation. ntdll: Fix HeapWalk with empty uncommitted consecutive subheaps.