708069 - takes two seconds to render ad header of www.autoblog.com (hardware acceleration, gradients & transparency, oh my!)

Status: RESOLVED WORKSFORME

(Core :: Graphics, defect)

Description

[Christopher Blizzard (:blizzard)]

1. Load the URL: www.autoblog.com/2011/12/06/2013-mazda-cx-5-first-drive-review/
2. Note that it takes a long time to load & render the page
3. If you switch tabs and then back to the page, it can take about 2 seconds to render.
4. If you scroll down on the page and then switch back and forth between tabs it's very fast, so the problem is just the very top ad header

Tested on a Nightly with Windows 7.

Comment 1

[Christopher Blizzard (:blizzard)]

OK, so it's actually an ad header that doesn't always show up.  Trying to capture it.

Comment 2

[Christopher Blizzard (:blizzard)]

Attachment: zip file of the page as rendered

Comment 3

[Christopher Blizzard (:blizzard)]

The perf problem comes from this style rule on the top of the page:

#ad_banner {
  background-image: -moz-linear-gradient(63deg, #151515 5px, transparent 5px),
                    -moz-linear-gradient(243deg, #151515 5px, transparent 5px),
                    -moz-linear-gradient(63deg, #222222 5px, transparent 5px),
                    -moz-linear-gradient(243deg, #222222 5px, transparent 5px),
                    -moz-linear-gradient(0deg, #1B1B1B 10px, transparent 10px),
                    -moz-linear-gradient(#1D1D1D 25%, #1A1A1A 25%, #1A1A1A 50%, transparent 50%, transparent 75%, #242424 75%, #242424);
}

Comment 4

[Christopher Blizzard (:blizzard)]

Attachment: reduced test case

Comment 5

[Christopher Blizzard (:blizzard)]

Looks like the page just uses -moz-linear-gradient with transparency and that is just plain expensive on Windows.  It makes this page super-slow.

Comment 6

[Christopher Blizzard (:blizzard)]

Note: if I disable hardware acceleration the problem goes away.

Comment 7

[Boris Zbarsky [:bzbarsky]]

Bas, this sounds like your sort of thing!

Comment 8

[Christopher Blizzard (:blizzard)]

Hi, Bas!  What's up, baby?

Comment 9

[(mostly gone) XtC4UaLL [:xtc4uall]]

This (given URL and Attachment 579455 [details]) is fixed/WFM with Bug 823147 fixed.

Comment 10

[Benoit Girard (:BenWa)]

Also WFM in today's nightly