If I have six or seven tabs open in Firefox, and I need to close it down for performance or other reasons, is there a way to save that state of tabs so the next time I open Firefox it'll reopen those tabs?
Tab Mix Plus, an add-on for Firefox, has a feature called Session Manager. It will reload the state of all tabs and windows when you restart Firefox.
I think there is already a session manager in Firefox 3.5 but the version included in Tab Mix Plus is much more advanced.
If you don't need all the features of Tab Mix Plus, there is also a Session Manager add-on but I never tried it, as TMP has tons of other features.