Why do you close it? I also use windows, never have more tabs than I can read their titles, and never close Firefox (except when some js crashes it, like browserstack.com)

Firefox is my browsing (err) browser (I like tag bookmarks too much).

I use chrome to develop with as I like their tools much better than firebug which, to me, is very slow in comparison. Chrome I close out relaunch semi-frequently (crtl-w spam, oops), but still keep it open, because why not?