[psychometry]

In Chrome: 1Password, AdBlock, a Gmail checker, a cookie editor, FlashBlock, Ghostery, Hacker News Enhancement Suite, Imagus, Reddit Enhancement Suite, Stylish.

Once I'd installed the corresponding Firefox add-ons, the UI became too unresponsive too often for me to put up with it.

[zxcvcxz]

I have most of those installed (plus some others) in FF Nightly and I'm running fine.

It sounds to me like one of the plugins probably has a bug.