Firefox page loading problem - pages load quick in IE

I am having issues lately with Firefox. This isnt constant but happens intermittently waiting to load for 10 minutes then loading and working well for a few minutes before slowing to a crawl again. All pages load fine in IE when I test it at the same time.

Test pages were:
myspace
google
wikipedia
192.168.1.1 - router page

All 4 showed loadtime in firefox. I started firefox in safe mode and also had the same issues with wait times. I dont know why it is just firefox and why it happens intermittently.

A related issue is music or youtube videos would stop playing after I played my first song or video. With youtube videos, the whole video downloads but would freeze after 2 seconds of playing. Works fine in IE, issue only happens in Firefox but corrects when I close and reopen browser.

Maybe reinstalling browser would fix it, but I would like to know why it is happening.

I am not running any firewall.
I am running 2 codec packs, ffdshow and vista codec pack.
cant think of anything else.

 

thanks for the tips. I dropped ffdshow and it fixed lots of problems.