Improving portability advice

If the arrays are dynamically allocated, slab allocator (for example) might do this. I once looked at a case that was allocating a bunch of individual pointers that all got rounded up from 8 to 32 bytes, meaning 75% of each allocation was unused. It makes sense that the allocators work that way, but if you don't know that and do this sort of thing hundreds of times, and especially if the memory being allocated happens to be something like 2**n + small_amount, you can accidentally waste a lot of memory.