A lot of people that have switched to the Google Chrome browser have done so because Mozilla Firefox seems to run slower. It turns out that there is a fix that helps Firefox run a bit faster. You can have the cache load from your memory instead of loading cache images and data from the hard drive. Here is how you do it:
1. Type about:config in the address bar.
2. Type browser.cache into the field where it says Filter.
3. Set the browser.cache.disk.enable preference name to false by double clicking it.
4. Set the browser.cache.memory.enable to true by double clicking it.
5. Right click and hit New -> Integer -> Type browser.cache.memory.capacity
6. Press OK and then set the type to 100000 and press OK. (This is the equivalent of 100MB).
7. Restart Firefox
If you have a lot of memory to work with, feel free to change the number to something higher.