Well that's pretty big, no pun intended haha. What I would do is cutting the file in parts. What I mean is perhaps you have a very big site with a lot of stuff going on and maybe a CMS, I would recommend that you call the css that you need only in the page the user is seeing. Why make him load every part of the CSS of the whole site when maybe he is just seeing the home page. That's what I would do. Hope it helps you.