Oh, okay, it's not that bad. So long as you don't have too many add-ons installed. But, you know, as a "developer" that has to debug other people's broken web stuff, you need those add-ons. And, you know, they're actually quite nice.
Anyway, running the same set of add-ons on Firefox for development and plain browsing is not working out.
Of course, none of this is rocket science, or even new, so everybody else probably knows anyway.
I now have one "firefox -P default" icon and one "firefox -P development" icon on my panel, and browsing is fast again (I'd totally forgotten quite how fast) and development is still featureful.
(And, I guess, if you're into that sort of stuff, you can use a totally different profile for your House erotica fanfic writing persona and another for your respectable normal persona.)
This is where the Google browser sync is awesome (assuming you don't mind google knowing what websites you are looking at) so you can have the same bookmarks across all your profiles. Of course there is probably a simpler and less network intensive way to keep all your profiles using the same bookmark file (hello symlink!), but then you don't get the benefit of having your bookmarks mirrored for your use on any firefox browser.
@brad using a symlinked bookmarks file has issues when adding bookmarks to one of your sets of firefoxes the symlink gets moved on start up for 'backing up the bookmarks file'.