My browser just randomly updated itself before my most recent log-in, today (Feb 18), and the browser is hanging up and running VERY slowly ever since. I think it said it was updating an add-on, but I can't tell what was updated. Anyone else having this problem?

It happens on pages with animated ads in particular. It's always run more slowly on pages with animated ads, but it's just totally crawling since this unwanted, automatic update. I'm even starting to get scripting errors that occur minutes after the page hangs up, something I thought I'd solved.