Actually having experience. Oh and the fact that I just set up a new windows 7 VM and from the fresh install on the DVD and how it ran, compared to after applying all updates it lost all of it's speed.
Nothing installed but windows updates. on the exact same hardware. Absolute solid proof to me.
I've seen this before. I do a fair bit of computer repair on the side, and just recently someone brought me a Windows 7 Home Premium install that was acting this way. I cleaned the computer of malware and junk programs, but it was still using 50%+ memory when idle. It turned out that the windows update service itself was causing the problem. The biggest ram hog was svchost running makecab.exe repeatedly, eating up nearly 1GB of memory all by itself.
It turned out the issue was actually a corrupted