On a 32-bit operating system, 32-bit programs run relatively slower when they run on a 32-bit OS

Question

I read about WOW 64 here http://en.wikipedia.org/wiki/WOW64

and found out that its layer in 64-bit Windows runs 32-bit programs.

So, can I assume that 32-bit programs run relatively slower on a 64-bit OS when they run on a 32-bit OS.

I see the benefits of accessing more than 4 GB of memory on a 64-bit OS. But did this benefit necessarily offset the small overhead added by the WOW64 layer? Are there any other advantages of 64 bits that make up for this.

Answer 1

The main advantage of a 64-bit system is that it allows applications in 64-bit mode, which, in turn, is primarily useful if you need to access more than 4 GB of memory. If you have this requirement, using a 64-bit system is your only choice. Your application will use 64-bit code, so WOW64 will not be used and therefore will not cause problems.

If you really have no requirement to use more than 4 GB of memory in one process, it becomes debatable whether there will be an improvement in 64-bit Windows. You might need 64-bit Windows if you want to use more than 4 GB of main memory (although you can also use PAE for this, which has its drawbacks). However, on a 64-bit system, you can run 64-bit applications. With AMD64 processors, 64-bit mode can be faster than native 32-bit mode because the processor has more registers. Whether this small gain is an advantage is an insignificant loss. WOW64 depends on your application.

Personally, I believe that many people install 64-bit Windows because they do not fully understand the consequences of this, but they believe that they are safe (which they cannot, due to the lack of drivers).