Windows 7 64bit hangs with memory intensive programs, 32bit does not

Previously before my old harddrive failed I was using 32bit Windows 7. When using a memory intensive program such as Photoshop I wouldnt have any problems. There would be a slowdown when doing something big/ram intensive to an image but I could still use other programs fine. Since installing Windows 7 64bit, doing the exact same things to photos in Photoshop causes the whole computer to practically freeze, impossible to use any programs. Task manager says its using 89% of the physical memory. Same happens with other programs such as AutoPano which use a lot of ram, but not a single problem when previously using 32bit windows. Is this a 64bit problem and should I reinstall and go back to using 32bit, or is there something else wrong?
AMD Phenom triple core 2.1Ghz, 3GB Ram, Windows 7 Ultimate

Question Info

Last updated March 15, 2018 Views 317 Applies to:
After thinking about it I realised the problems only seemed to occur after installing Windows 7 Service pack 1. Ive uninstalled it and now most of the problems have gone. Still not as fast as it used to be, but I can now run all my programs with significantly less freezing and not have to wait ages for them to open. Googling "Windows 7 Service Pack 1 performance" shows that I wasnt the only person with this problem
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