Windows 7 - Things slow down - Any ideas?

I've noticed when my machine up and running for a few days, things appear to slow down until a reboot is performed.

Most notably:

1) Time from Explorer start to a home page painting
2) Time from empty trash request, to confirmation appearing
3) Time to open windows
etc.

When I reboot, everything gets speedy again.

I originally thought the web issue (#1 above) could have been caused by temp files, cookies, etc, but I've cleared that stuff out and it's still slow until the reboot.

Any ideas? Is there a memory leak somewhere?

Thank you!

No, not memory leak... try reducing the Hardware acceleration of the computer or the DPI settings... have you tried them so far

No, I have not tried these things, but why would I want to reduce hardware acceleration?

why i am telling you to reduce hardware acceleration is because the unwanted programs will no longer automatically run on the background.... Other wise its your computer, i am only a suggestor, but you are the decider..... So its better you decide

I had the same trouble shortly after trying to install zonealarm from my vista harddrive. Do this, run the system speed thingy similar to the control alt delete program. It will show you processes and memory being used in a graphic format, start closing off system programs from that program, one by one, keep an eye on the graph, if it drops fast, then you found the culprit. uninstal the program that is causing it.
Chris.

open task manager, select to show processes from all users, check with process is hogging cpu. or better yet, capture a screen shot of task manager and share it.