Firefox Performance Preferences

A number of Third-Party/Unofficial Builders add performance preferences to their builds which can improve Firefox performance and the overall browsing experience. I don't use these in my builds as I like to stay as close to the Official Builds as I can even though I may personally use performance preferences in my local installations.

I did some testing with performance preferences and found about a 2% improvement in my JPEG rendering benchmark suite. What I do is use a text editor to add the lines below to the all.js file in the defaults\pref subdirectory off the main Firefox directory.

pref("dom.max_script_run_time", 5);
pref("dom.disable_window_status_change", true);
pref("content.notify.backoffcount", 5);
pref("content.notify.interval", 750000);
pref("content.notify.ontimer", true);
pref("content.maxtextrun", 8191);
pref("content.max.tokenizing.time", 3000000);
pref("content.interrupt.parsing", true);
pref("content.switch.threshold", 750000);
pref("network.http.pipelining", true);
pref("network.http.proxy.pipelining", true);
pref("network.http.pipelining.maxrequests", 8);
pref("network.http.max-connections", 48);
pref("network.http.max-connections-per-server", 32);
pref("network.http.max-persistent-connections-per-proxy", 16);
pref("network.http.max-persistent-connections-per-server", 8);
pref("browser.display.show_image_placeholders", false);
pref("ui.submenuDelay", 100);
pref("nglayout.initialpaint.delay", 500);
pref("browser.sessionhistory.max_total_viewers", 15);

User Prefs

I'm going to provide a list of user prefs that I find helpful for general browsing or to improve performance.
If my long vendor string is causing problems with an extension, you can always go and edit the all.js file in the defaults\pref folder and change it to whatever you'd like. (mmoy) may work best with finicky extensions.


In addition, I've heard some pretty good reports on a free product called FireTune that will change Performance Preferences without the user having to change about:config settings or edit Javascript files. Their product is available at

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Updated February 7, 2005. For comments and questions, send email to Vector.x64 @ (without the spaces).