6. Increase the cache size

As you browse the web so Firefox stores site images and scripts in a local memory cache, where they can be speedily retrieved if you revisit the same page. If you have plenty of RAM (2 GB of more), leave Firefox running all the time and regularly return to pages then you can improve performance by increasing this cache size. Type about:config and press [Enter], then right-click anywhere in the window and select New > Integer. Type browser.cache.memory.capacity, click OK, enter 65536 and click OK, then restart your browser to get the new, larger cache.