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I've seen other questions here asking about the advantages of running 64 bit programs over 32 bit and most answers say there's hardly a difference, unless they have to use an obscenely large amount of ram. So my question is, is it worse to run 64 bit versions? Do they on average hog more ram? I think I've noticed this with a few medium large programs, and I'd like to see if this makes sense.

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A 64-bit program uses twice as much memory to store a certain kind of data called a pointer: they're 8 bytes each instead of 4. Some programs need to store large numbers of pointers in memory, and may therefore use significantly more memory on a 64-bit system, but not all programs will be greatly affected. Some may show very little difference between 32-bit and 64-bit.

However, 64-bit programs have access to more CPU registers, which can help the program avoid needing to access memory quite as often. This can improve performance, since memory access is a bottleneck.

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  • I see. So if my program is generally idle (like an IDE), I'm better off running it in 32 if space is tight. I should reinstall all my software again..
    – yts
    Nov 20, 2014 at 4:20
  • Maybe, but you'd be better off just installing more RAM. That can also improve performance, system-wide — less disk thrashing.
    – Wyzard
    Nov 20, 2014 at 4:23
  • If I usually only use 2-3 gig of 4, is there still disk thrashing going on?
    – yts
    Nov 20, 2014 at 4:24
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    That's something only you would know, since you're the one sitting at the computer. But even if you have "enough" RAM for your applications, the operating system can use any "free" RAM as disk cache, which speeds up access to data on disk.
    – Wyzard
    Nov 20, 2014 at 4:27

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