to applying the tweak, first you need to add the line to your prefs.js, and then remove write perms on the file or else Mozilla will overwrite it on startup and remove your tweak, here's how to do it:
(First make sure Mozilla/Firebird and Galeon are closed before you proceed)
echo 'user_pref("nglayout.initialpaint.delay& quot;, 0);' >> ~/.mozilla/default/*.slt/prefs.js
chmod -w ~/.mozilla/default/*.slt/prefs.js
echo 'user_pref("nglayout.initialpaint.delay& quot;, 0);' >> ~/.galeon/mozilla/galeon/prefs.js
chmod -w ~/.galeon/mozilla/galeon/prefs.js
A Matter of Taste
This tweak isn't for everybody or all systems, try it out and see how it works for you, it may use a little more cpu, but some people like to see things rendered as they're downloading. Especially if you have a faster connection, or even if you don't, give this tweak a try and see if you like the 'zilla's speed with or without the delay.
Doesn't differ much from my PET from LONG ago.