[wellylug] 32 Bit vs. 64 Bit

[Rob Giltrap]

Gerald Roehrbein wrote:
> what's faster 32 Bit or 64 Bit applications?
Both, neither and it depends!

Here's some big generalizations but...

If you're running a 32bit program on a 32bit OS then it will generally 
run a fraction faster than something that uses the full memory 
addressing available in a 64bit system (we are only talking like 1% 
difference).

If you are using an AMD64 processor there are a number of additional 
registers available in 64bit mode (particularly floating point 
registers) so if your application does complex FP operations then it 
will likely run a good chunk faster in 64bit mode than 32bit mode. Not 
sure about the new Intel processors.

If you are using more than 4GB of physical ram then memory operations 
are going to be in general faster in 64bit mode.

Cheers.