Hi there, I know there are alot of websites around with info on speeding up firefox, but this is how to do it the proper way. The info is taken from tweakfactor.com and mozillazine.org, I'm just passing the info in an easier to read manner.
First of all you need to create a 'user.js' file in your Firefox Profiles directory, to do this make a .txt file in the folder shown below, depending on your OS:
You might need to turn on 'show hidden files'.
Windows XP/2000 C:Documents and Settings[User Name]Application DataMozillaFirefoxProfilesdefault.xxx.
Windows 95/98/ME C:WINDOWSApplication DataMozillaFirefoxProfilesdefault.xxx.
A couple settings of note - Firefox is allocated 4096 KB of memory by default and in this configuration we give it roughly 65MB as denoted by the last line. This can be changed according to what is used.
Fast Computer, Slower Connection
This configuration is more suited to people without ultra fast connections. We are not talking about dial up connections but slower DSL / Cable connections.
One of the changes made for this particular configuration is the final line where the status bar is disabled for changing web pages to save processor time.
Once you have finished adding the preferred code for your computer and connection speed you will obviously need to save the file. File > Save As > user.js
Thats it! I hope you find it useful, it has certainly speeded up my Firefox.