Comment by galangalalgol

Most games have to do this for performance reasons at some point and there are plenty of variants to choose from. Rust has libraries for some of them, but in c rolling it yourself is the idiom. One I used in c++ and worked well as a retrofit was to overload new to grab the smallest chunk that would fit the allocation from banks of them. Profiling under load let the sizes of the banks be tuned for efficiency. Nothing had to know it wasn't a real heap allocation, but it was way faster and with zero possibility of memory fragmentation.