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If you double the size of pointers (64 bit, up from 32 bit) then your program will take up more heap. This is especially significant for languages where everything is a heap allocation.

If you code does intresive computation with structures containing a lot of pointers, you’ll get much more cache miss when using 64 but pointers.

The performance hit can be quite heavy!

Cache is a limited resource, and you want as many pointers as possible to fit there.

It's bloat used properly, in the most literal sense. Your pointers are 64bit, but you always use less than 32bits. So, all your pointers are twice is big. This wasted space from bits you do not need is "bloat".