问题
Why do elements with the CSS position: fixed applied to them cause Firefox to eat 100% CPU when scrolling the page they are in? And are there any workarounds?
I've noticed this behavior on a few sites, for example the notification bar at the top of the page on StackOverflow. I'm using Linux in case that matters.
回答1:
This is bug #201307.
回答2:
It's a bug reported in bugzilla
Apparently a work-around (with mixed reports of success..) is to disable smooth-scrolling
Just disable smooth scrolling in Edit > Preferences > Advanced.
回答3:
As already stated, this is bug #201307. The workaround is to disable smooth scrolling:
Edit -> Prefrences -> Advanced -> General tab -> uncheck "Use smooth scrolling"
回答4:
This website has a fixed element "First time at Stack Overflow? Check out the FAQ!", and it's slow as hell in firefox. Works better with Opera and Chrome though. FF3, Windows XP, ATI.
回答5:
it eats CPU because the browser has to repaint the entire viewport every scroll change rather than just the newly visible area
回答6:
Are you sure that there's a direct link here? Have you created a static HTML page with fixed elements to verify your theory? Given how widely these CSS properties are used, I'd think someone else would have noticed it by now, whatever browser/OS you're running.
来源：https://stackoverflow.com/questions/67588/why-do-fixed-elements-slow-down-scrolling-in-firefox