`background-size:100% or cover` causes javascript to slow

Question

In FF 17 :

body{
  background:  url('foo/images/flowers.jpg');
  background-size:  100%;
  background-attachment:  fixed;
}

causes the page to move slow, this means the animation and even the mouse pointer trailing across the screen.

Once I remove the background image all is fine.

To troubleshoot I removed the Base64 representation of the image and linked directly to the image as shown above.

I can continue to isolate in this manner, but I'm wondering if this is a known issue.

---

Isolating further it is this property causing the issue.

  background-size:  100%;

Answer 1

这似乎是background-size:100% or cover的问题background-size:100% or cover已在新FF修复的background-size:100% or cover 。