| One of the best uses of 64 bit (or simply having wider instructions) is that you can A) work with larger numbers and B) deal with more data in a given instruction. From this standpoint, it's a vastly superior architecture. more data in an instruction (such as bringing in 6 bytes instead of 4) means you can get done in one clock cycle what it used to take you in 2 or even more (if you count a branch miss, or a fetch instruction, blah blah blah).
simply put, wider instructions means you can add new instructions and extensions, that weren't possible before, and optimize things down to one hardware instruction that used to take more. It's like a temporary clock speed doubling or tripling for those few issues.
Since I'm a DBA, I want my RDBMS to be a 64 bit version. But I still won't opt for a 64 bit O/S because some other things still don't work the best with it.
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