Using about:config is a powerful way to customize your Firefox. Combined with the previous userChrome.css tweaks post and Firefox Add-ons (post coming soon), you can completely personalize your Firefox experience. Today I will be talking about how to modify about:config, give some online resources of tweaks you can do, and tell you which ones I personally recommend. Ready?

How to modify about:config in Firefox 2

Open a new tab and type “about:config” (without quotes) into your location bar (also called address bar) and press Enter. Firefox will display a very large set of key/value pairs for a ton of advanced settings. Type in the “Filter:” field to narrow by
preference name. You can double-click or right-click on a row and select Modify (for String or Integer fields) or Toggle (for boolean values). There is another tutorial here.
Now you probably don’t have all week to go through these, so that’s why I am here to list the most interesting changes.

List of online about:config references

• Complete (but slightly old) list of about:config entries
• Ten Mysteries of about:config
• Top Firefox 2 config tweaks [Lifehacker]
• Hacking Firefox: The secrets of about:config

Personal favorite about:config tweaks

• Set browser.cache.disk.capacity set to 100000. This will set the maximum disk space for the browser’s cache to ~100Mb
• Set browser.cache.memory.capacity to 100000 as well. Also note that you can set
  browser.cache.memory.enable to false forcing Firefox to disable the cache but also to keep it self-contained. (this will make pages that you visit often to be slow and stay slow, though so be careful).
• Set browser.search.openintab to true so that the searches from the search bar go into a new tab instead of the current one.
• Set browser.sessionhistory.max_total_viewers to 1. This determines how many web pages to store in the cache. Setting to 0 saves about 4Mb of cache per page, but slows things down for back/forward operations.
• Set browser.sessionstore.max_tabs_undo to the number of tabs you can undo. The higher the number the higher the memory, so I set this to 1 because I still seem to close tabs accidentally, but usually only 1
• Set browser.tabs.loadDivertedInBackgroundset to true. This forces Firefox to open new links in the background so that it doesn’t steal focus from the page I am still trying to frickin’ read!
• Set browser.tabs.tabMinWidthset to 0 to disable tab scrolling, otherwise you can set it to the minimum allowable width of a tab (in pixels) before tab scrolling comes in.
• Set browser.urlbar.autoFill to true. This will enable auto-completion.
• Create and set browser.urlbar.hideGoButton (boolean) to true to remove that Go button you never use anyway.
• Set layout.word_select.eat_space_to_next_word to false so that when you double-click on a word to select it, Firefox does not select the space to the right of that word
• Set network.http.pipelining to true allowing for the use of HTTP/1.1 pipelining.
• Set network.http.pipelining.maxrequests to 16 so that Firefox can make more simultaneous connections for faster downloading
• Set network.http.proxy.pipelining to true (same as network.http.pipelining with proxies.
• Set network.prefetch-next to false. I think this cuts down memory usage because when set to true Firefox prefetchs “hinted” documents and store in the cache (e.g. the 1st Google Search result)
• Create and set nglayout.initialpaint.delay (integer) to 0 so that Firefox starts to render a page immediately (defaults to 250ms).

There are tons more tweaks, but these are most of the ones I use. Share your about:config tweaks in the comments!