I'm on a 64 bit OS and I'm running several Linux virtual machines. I'm wondering if there is any benefit to a 64 bit Linux distro over a 32 bit one. I know that a 64 bit OS allows over 4GB of RAM, but most of my VMs don't use that much. Is there any point to using a 64 bit distro over a 32 bit one for performance reasons? A 32 bit OS will (in theory) use less memory due to smaller pointers and instructions, so I'm a bit skeptical to switch to a 64 bit OS if I'm not going to use more than 4GB of RAM for the VM. Will instructions that use 64bits (int64 and doubles) process any faster?
Bear in mind what the future brings. Memory is pretty cheap these days, and often a good choice to improve performance (just threw out the original 2GB memory in a Macbook and placed 8GB inside - it does wonders).
If you have 64 bit Linux VMs you can later just copy them onto your new machine with more memory and be done. My old PC had a 32bit Linux installed and I never wanted to go through the trouble of a new install for using more memory, though I did have use for it. With regards to performance, I can't tell the difference between the two, but that's just because I never upgraded a 32bit machine to 64bit. I'll probably do that in the coming days with my old PC as I prepare it for my kids. If I see any noticeable difference, I'll post here.