[burfog]

I do hundreds of tabs. The UI is fine, but performance is not at all OK.

The tab UI works because it is part of a larger 3-level system. There are tabs, windows, and virtual desktops. With 10 at each level, you can handle 1000 tabs... except for the performance.

It's important to avoid running things on pages that aren't in focus or even in view. It's important to avoid walking data structures that scatter nodes all over the address space, causing swap access and cache misses. Watch your RSS. Keep those extra tabs idle. Make sure the "Esc" key and the stop button actually work, stopping everything (all tabs, all video, all animation, all audio, etc.) until the user explicitly asks for something to run again.