Accelerating Firefox’s rendering time

If you use Firefox as your daily browser, and you’re not using Indic or any CJK script as your Firefox locale, you can disable the Pango renderer, which makes Firefox support these languages, but also make it (much) slower.

Before disabling Pango, i’ve loaded a big HTML page (the PHP reference) in Firefox, and watched the CPU time used by Firefox when the page was fully loaded. Of course the HTML page was stored on my hard drive to avoid network issues.
With Pango enabled (the default), it took 1 minute and 12 seconds to load the page.
Now, let’s disable Pango. Use your favorite editor to open the file name given by typing :

user$ which firefox

As you see, the Firefox executable is in fact a shell script that sets up the environment before actually launching Firefox. Look for the line that contains MOZ_DISABLE_PANGO. You’ll see those two lines:

# MOZ_DISABLE_PANGO=1
# export MOZ_DISABLE_PANGO

Simply uncomment these two lines:

MOZ_DISABLE_PANGO=1
export MOZ_DISABLE_PANGO

And you’re done !
My big HTML page, after having disabled the Pango renderer, took only 40 seconds to load. Note that you won’t lose any Firefox functionality, the Pango renderer just permits to support some exotic languages.