Firebug slows down Firefox no more!

Firebug slows down Firefox significantly. It's most noticeable when opening Gmail.

To solve this, use Firefox profiles. You can run multiple instances of firefox with different profiles.

$ firefox -P coding --no-remote

That will start a new Firefox instance with "coding" profile. When plugins are installed, they are attached to a specific profile. To create/manage profiles, close Firefox and run:

$ firefox -ProfileManager

Don't you love Firefox?