Firefox Loading Issues

There are a few things that have popped up with Firefox that really bug me, and force me to use Internet Explorer to view certain sites. For example, when I access any of my site's cPanel with Firefox, it just takes VERY VERY VERY long to load, but when I use IE to load the cPanel is loads in a second.

Another problem with Firefox is that sometimes I can't see certain pictures, for example, the eBay site appears all broken, not showing most of the pictures - why is that?

These problems are becoming really annoying, any ideas?