When I go to the URL in the URL field I get a hang or a high CPU usage. Before bug 300030 it was about 30-35% and after bug 300030 85-100%.

Would be nice to have a minimal-ish testcase...

Thanks for attaching the page, Ria. I've minimized that page to this, thus far. I still see a cpu increase when testing between 2006-12-07 and 2006-12-08 builds. (unfortunately, I have difficulty with quantifying it with a timeout, that would make minimizing easier)

So is this Windows-only? I don't see any CPU usage on Linux on that testcase once it finishes loading...

Sorry, should have said it, you need to click on the runscroller button to begin testing.

Hmm. Yeah, a profile doesn't show anything unexpected... about half the time spent in reflow, half elsewhere...

Cut out a bunch of the JS, didn't touch the HTML

This is a somewhat minimized testcase. I didn't try to change the javascript. Press the "runscroller"-button for the test. The CPU usage doesn't jump extremely high when you remove one of the following: - the 'height="585"' of the <td> - the 'style="width: 760px;"' of the <div id="ticker"> - move the entire '<div id="ticker">' out of the <table>

I just tried profiling this on Mac, and we spend all our time painting. Removing the height from the table cell drops CPU usage from 40% to 20% or so. I wonder whether the height matters just because we end up invalidating a bigger area or something? I still wouldn't expect the repaint here to be all that expensive here...

...could also be triggering special height reflow, requiring an extra pass (and perhaps additional invalidation resulting from the oscillation between the two results).

(In reply to comment #7) > Created an attachment (id=292949) [details] > Minimized testcase > > This is a somewhat minimized testcase. I didn't try to change the javascript. > Press the "runscroller"-button for the test. > > The CPU usage doesn't jump extremely high when you remove one of the following: > - the 'height="585"' of the <td> > - the 'style="width: 760px;"' of the <div id="ticker"> > - move the entire '<div id="ticker">' out of the <table> ranges 5-15% cpu for me with Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2a1pre) Gecko/20090621 Minefield/3.6a1pre (.NET CLR 3.5.30729)

Works for me using testcases that had been attached here using Lastest Nighty 25: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:25.0) Gecko/20130730 Firefox/25.0