Maybe not the best place to ask, but I have a question on Firefox. If I install an extension, but leave it disabled, will it be completely disabled, ie take no memory, add no load time (except for update checking), etc...
Any addon to a browser is inactive once disabled. IE and FireFox alike use very little memory unless you see a page freeze up where that then demands cpu time. Even opening up multiple windows is far from resource hungry in that sense while the bandwidth depending on the type of connection will be deminished greatly at times.