Enable pipelining

Browsers are normally very polite, sending a request to a server then waiting for a response before continuing. Pipelining is a more aggressive technique that lets them send multiple requests before any responses are received, often reducing page download times.

To enable it, type about:config in the address bar, double-click network.http.pipelining and network.http.proxy.pipelining so their values are set to true, then double-click network.http.pipelining.maxrequests and set this to 8.

Keep in mind that some servers don’t support pipelining, though, and if you regularly visit a lot of these then the tweak can actually reduce performance. Set network.http.pipelining and network.http.proxy.pipelining to false again if you have any problems.

Render quickly

Large, complex web pages can take a while to download. Firefox doesn’t want to keep you waiting, so by default will display what it’s received so far every 0.12 seconds (the “content notify interval”). While this helps the browser feel snappy, frequent redraws increase the total page load time, so a longer content notify interval will improve performance.

Type about:config and press [Enter], then right-click (Apple users ctrl-click) somewhere in the window and select New > Integer. Type content.notify.interval as your preference name, click OK, enter 500000 (that’s five hundred thousand, not fifty thousand) and click OK again.

Right-click again in the window and select New > Boolean. This time create a value called content.notify.ontimer and set it to True to finish the job.

Faster loading

If you haven’t moved your mouse or touched the keyboard for 0.75 seconds (the content switch threshold) then Firefox enters a low frequency interrupt mode, which means its interface becomes less responsive but your page loads more quickly. Reducing the content switch threshold can improve performance, then, and it only takes a moment.

Type about:config and press [Enter], right-click in the window and select New > Integer. Type content.switch.threshold, click OK, enter 250000 (a quarter of a second) and click OK to finish.

No interruptions

You can take the last step even further by telling Firefox to ignore user interface events altogether until the current page has been downloaded. This is a little drastic as Firefox could remain unresponsive for quite some time, but try this and see how it works for you.

Type about:config, press [Enter], right-click in the window and select New > Boolean. Type content.interrupt.parsing, click OK, set the value to False and click OK.

Block Flash

Intrusive Flash animations are everywhere, popping up over the content you actually want to read and slowing down your browsing. Fortunately there’s a very easy solution. Install the Flashblock extension and it’ll block all Flash applets from loading, so web pages will display much more quickly. And if you discover some Flash content that isn’t entirely useless, just click its placeholder to download and view the applet as normal.

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 (2GB or 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.

Reduce RAM usage when Firefox is minimized

Go to about:config, right-click anywhere and select New-> Boolean. Name it “config.trim_on_minimize” and set it to TRUE.