There are so many things wrong with this picture... For starters, that's a lot of tabs. Firefox is probably having trouble managing all that. I am guessing that you have quite a bit more than 2 to 3 gigs of RAM in your machine, but since you are on Windows, Firefox is a 32-bit application. This means it has some restrictions, one of them being that it cannot access any more than about 3 gigs of RAM. Also having that many tabs is probably bogging down your processor a bit... If you can, close some tabs, but if you can't really do that, you could give Waterfox a shot. It is a 64-bit version of Firefox for Widows, so it should be able to access more RAM, which should, in theory, make Firefox faster when dealing with a ton of tabs. Also check your CPU usage to make sure that it's not too high.
@SamiLaine Why should it matter how many tabs are open? Tabs that aren't being used at the moment should be written to disk and not occupy memory or CPU at all. – endolith – 2016-12-19T02:48:03.227
I'm prone to ask why would you have 180+ tabs open? What I mean is not to belittle your problem/question, but this just sounds like an overkill and most likely is solvable by redefining your workflow in such a way that you could do with a smaller number of tabs. – Sami Laine – 2014-04-12T08:27:49.203