The only problem I have with Firefox these days is an occasional crash. Otherwise it works fine and I don't find it sluggish at all. I have many tabs open usually and am using:
All in-One Sidebar
ColorZilla
Firebug
RankChecker
RefControl
SEO for Firefox
SEO Toolbar
Web Developer
and a few more that are disabled like Sothink SWF Catcher.
Currently FF is using 175mb on my machine which has 4gb of ram in it (but is on XP pro so only uses 3mb).
I would suggest adding more RAM to your machine if you are running less than 2gb.
Defrag your HD.
Select "run" and type "msconfig" and disable any start up apps that you don't need that are also hogging resources.
etc.
All in-One Sidebar
ColorZilla
Firebug
RankChecker
RefControl
SEO for Firefox
SEO Toolbar
Web Developer
and a few more that are disabled like Sothink SWF Catcher.
Currently FF is using 175mb on my machine which has 4gb of ram in it (but is on XP pro so only uses 3mb).
I would suggest adding more RAM to your machine if you are running less than 2gb.
Defrag your HD.
Select "run" and type "msconfig" and disable any start up apps that you don't need that are also hogging resources.
etc.