See https://en.wikipedia.org/wiki/64-bit_computing#Pros_and_cons
After listing many significant advantages of 64-bit architectures over 32-bit ones, it says:
The main disadvantage of 64-bit architectures is that, relative to 32-bit architectures, the same data occupies more space in memory (due to longer pointers and possibly other types, and alignment padding). This increases the memory requirements of a given process and can have implications for efficient processor cache use.
