Comment by galangalalgol

Yeah, profiling is your friend. I forget if it's called a sharded slab or a buddy allocator, but the one where you have different preallocated buffers chunked at different sizes. Any time you allocate you are given the smallest chunk that will hold what you asked for. Profiling gives you optimal size boundaries as well as the number of each. Add a safety margin and off you go. Super fast allocation and guaranteed no fragmentation. In a c++ codebase overloading std::new to do this is probably the easiest way to get your allocation performance back and avoid fragmentation.