32 or 64??

[Chris Jones]

Hi,

> Depends what you consider faster.  Most people won't notice any 
> difference on the desktop, since your bottleneck is almost entirely 
> going to be hard drive (in particular, head seek time).  If, however, 
> you are are performing a cpu intensive task (something that keeps your 
> processor going at 100% plus) then there is a significant speed boost. 
> I can clearly see over 15% speed increase in bzip / 7z compression as 
> well as video encoding.

This is completely true. However, its worth noting that the speed increase seen with 64 bit number crunching isn't completely due to the 64 bit'ness, but mostly other factors. The GCC compiler knows for instance that all 64 bit CPUs have the SSE instruction set, whilst not all 32 bit ones do. Therefore, when building 64 bit binaries it can safely make use of these instructions, for instance in mathematical calculations where they can make a big difference. For 32 bit binaries to be fully compatible with all 32 bit systems, it cannot use these instructions. 

Most 32 bit CPUs do have SSE though, and if you where to force GCC to include these in 32 bit builds, the speed difference between them and 64 bit builds would be much less.

cheers Chris