I have a Win7 64 bit PC that works for approx 3 to 4 hours before it 'decides' to start pausing between actions. The pause is no less than 5s but typically longer. The actions I mention could be anything from opening a new website in a new tab; Opening a word document; Performing house cleaning; Installing or uninstalling an application, etc.. the other odd part is that once I have a website open (for example) then browsing around in that site, so long as I remain in that tab, is lightning fast. If I go to open a link in a new tab I get the same delay.

I've sat and stared at task manager but it shows no stress on the threads or excessive use of RAM. I've cleared my temp files, my cache(s), etc... and no change. Now, here's what I've checked as best I can

- Fans
- Drivers
- Windows updates
- Registry
- and I'm sure there's more I've forgotten.

Any suggestions on where to look next or ideas as to what might be causing this?

edit: I should add that a system restart brings me back to a good working condition.