I don't quite have that many tabs open but I find that grouping tabs into separate browser windows and taking advantage of your window manager goes a long way.
https://addons.mozilla.org/en-US/firefox/addon/tree-style-ta...
It allows you to use your tab-list in a hierarchical way, sort of like a filesystem. I group things under obvious roots, and then collapse it till needed.
And I can always switch to a different wm altogether if I'm not comfortable.
Obviously you can easily achieve the same thing in separate windows as well, so ultimately I suppose it doesn't make a huge difference, but it's the way I find makes for the biggest difference in separating workspaces.