Comment 5 for bug 16465

This is the same as the upstream bug:
https://bugzilla.mozilla.org/show_bug.cgi?id=137584
which has been there for some time.

The root cause of the problem seems to be (1) use of an algorithm which is more
cpu-intensive than the (pretty evil) page designers expect (which I assume means
more cpu-intensive than common versions of IE) combined with (2) a failure to
limit the amount of work done pursuant to a page's javascript (which turns it
from a `doesn't render' into a `makes program difficult/impossible to use').

In my tests firefox sometimes locked up completely but usually it was able to
respond to incoming UI events sufficiently well to get off the offending page.