My browsing habits cause me to open lots of windows and tabs, either related to different projects I'm working on or things I may want to read later. I use OSX and use about 5 spaces with multiple windows in each space. The problem is eventually I'll have around 200 or more tabs open (spread over 15-20 windows) that I don't want to close. Needless to say, my computer's performance starts to degrade. As I write this on my mobile, Safari on my laptop is locking up the computer. I used to use Chrome but found better performance with Safari.

What I'd like to know, is there a graph of browser performance based on tab usage? I don't need a browser that keeps all tabs active. It would be great if the browser could increase performance by "putting tabs to sleep". Or if there was some sort of tool for saving a "workspace" of tabs that you could reactivate the next time you are working on that project. What sort of solution can you recommend to solve this problem?