In the case of RC5, which is a 32bit algorithm, a 64bit processor provides no real advantage to the algorithm, in fact it can be a slight disadvantage. Most 64bit processors, however, provide other amenities that actually allow a slight advantage over 32bit cores.

For OGR however, 64bit processors can substantially improve performance as fewer registers are needed to store the basic OGR data structure and thus fewer instructions are required to manipulate it.

On some platforms, X86 and AMD64, for example, different cores are required or desired for the 32bit and 64bit clients. These cores are usually optimized differently and thus have differing performance. Cores are occasionally modified and improved, which can result in performance differences arising between client versions. Further to these factors, the compiler or options used when building a client port may affect the core performance.