http://www.neowin.net/forum/index.php?s=07b128c3d6534b6d39e5859d532ca9d1&showtopic=420720


I recently started developing 64-bit apps. The 64-bit apps run
significantly faster than 32-bit apps.

The primary reason being there are more registers in 64-bit than in
32-bit. Also some of the bigger word sizes help a lot in copying
string variables.

To give you numbers, my applications which does heavy text
processing, dropped from 3 secs per 10000 operations in 32-bit to
200ms in 64-bit mode. The app uses the same amount of memory for bot
32-bit and 64-bit.

Also Windows 64-bit low-fragmentation heap allocator seems to be
significanlty better performant than the 32-bit allocator.

Your applications should be 64-bit to notice the difference. Running
32-bit apps in 64-bit OS will not provide any speed boost in most
cases