Re: Mixed boxed/unboxed arrays?

Could you use `StablePtr` for the keys?

That might be an option, but I have no idea how performant stable pointers are and manual management is obviously not ideal.

How does the cost of computing object hashes and comparing colliding objects compare with the potential cache miss cost of using boxed integers or a separate array? Would such an "optimisation" be worth the effort?

Literature on hash tables suggests that cache misses were a very important factor in running time (in 2001): https://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.25.4189 I don’t know whether it has become less or more important now, but I have been told there haven’t been that many advances in memory latency.