If you find that your Firefox browser is working very slow, you can try using a Firefox add-on - Fasterfox. Fasterfox helps you boost your Firefox performance and provides you with network tweaks.
Features:
Dynamic speed increases can be obtained with Fasterfox's unique prefetching mechanism, which recycles idle bandwidth by silently loading and caching all of the links on the page you are browsing.
Fasterfox allows you to tweak many network and rendering settings such as simultaneous connections, pipelining, cache, DNS cache, and initial paint delay.
A millisecond accurate page load timer tests the effectiveness of your settings.
A popup blocker for popups initiated by Flash plug-ins is also included.