2) Location Bar (Set number Auto Complete URL at Address Bar)
This is a good hack to trim down that huge auto-complete list on your URL bar. By default it displays maximum 12 URL
browser.urlbar.maxRichResults = #
Enter Number at # (3,10,12 etc)
3) Stop Displaying Website Icon (Favicon) in Address bar & On Tab
browser.chrome.site_icons = False
4) Disable Prefetch (Helpful for frequent Google searcher, low-speed internet connection or low RAM)
network.prefetch-next = False
5) Extend Spell check to forms
layout.spellcheckDefault = 2
Change Value from 1 to 2
6) Disable Blinking Text
browser.blink_allowed = False
7) Speed Tweaks
network.http.pipelining false to true
network.http.pipelining.maxrequests 30 to 8
network.http.max-connections 30 to 96
network.http.max-connections-per-server 15 to 32
network.http.max-persistent-connections-per-server 6 to 8
network.http.pipelining.ssl false to true
network.http.proxy.pipelining false to true
20) Fast Scrolling Across Tabs
Fast Scrolling Across tabs
toolkit.scrollbox.scrollIncrement =75
( 75 is number of pixels to scroll at a time when scrolling the tab strip’s scrollbox. (Default: 20)
21) Auto Complete URL while You type at address Bar
Auto Complete URL
browser.urlbar.autoFill=True
Many of above about:config hacks are available in Older Firefox Version, at the end if some thing goes wrong then feel free to restore your about:config to older setting see the below image of how to restore about:config