32bit vs 64bit

[Jimmy Tom_2]

Anyone know of any whitepapers that discuss performance improvement of recompiling C++ code from 32bit to 64bit?

thanks

[H.Merijn Brand (procura]

No, but the performance depends on more than one thing.

Every program has a startup penalty in 64bit (t.i. 64bit startup is a bit slower than 32bit startup). If you have a lot of process spawns you will notice.

If you however have only one huge process that does a lot of 'long long' calculations, you'll notice a performance increase. Same for access for files >>2Gb

Just my ??? 0.0005

[A. Clay Stephenson]

Your best bet is to probably do a search on 64-bit and performance. I can tell you the short answer because I've measured it. In almost every case 32-bit is faster than 64-bit. You should really think of 64-bit as a resource enabler rather than a performance enhancer. If your application can make use of large dynamic arrays or caches then it might indeed outperform it's 32-bit counterpart but I think that you are going to find that for the vast majority of application there is a performance hit for 64-bit.

[Bill Hassell]

As mentioned, 64bits for a program will not make the program run faster. Instead, it removes addressing limitations. If your program doesn't need thousands of megs of memory, then leave it as a 32bit program.