179155 - CSS opacity is slow

Status: RESOLVED INCOMPLETE

(Core Graveyard :: GFX, defect, P3)

Description

[Max Kanat-Alexander]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.2b) Gecko/20021106
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.2b) Gecko/20021106

I was working on a page with a fixed background, so I wanted it to show
partially through my DIVs. However, when I set -moz-opacity: 0.9 on the DIVs,
scrolling down the page became _much_ too slow.

Reproducible: Always

Steps to Reproduce:
1. Create a page with a fixed background attachment.
2. Set any -moz-opacity on anything on the page.
3. Put enough text on the page to make the page scroll.
4. Scroll the page
Actual Results:  
Mozilla scrolls jerkily down the page.

Expected Results:  
Scrolling should be exactly the same as it always is, easy and fluid.

Comment 1

[Max Kanat-Alexander]

Attachment: A reduced testcase

Comment 2

[Hixie (not reading bugmail)]

->GFX

Comment 3

[Kevin McCluskey (gone)]

-> dcone

Comment 4

[Markus Hübner]

Roc, isn't that related to the things you are currently working on?

Comment 5

[Robert O'Callahan (:roc) (email my personal email if necessary)]

Markus, can you make sure that all opacity bugs are assigned to me, and make all
opacity-related performance bugs depend on 195883.

Comment 6

[Markus Hübner]

sure - will keep an eye on it.

Comment 7

[Zibi Braniecki [:zbraniecki][:gandalf]]

This is a dupe of bug 193849.

*** This bug has been marked as a duplicate of 193849 ***

Comment 8

[Boris Zbarsky [:bzbarsky]]

I'm not convinced of that....

Comment 9

[Zibi Braniecki [:zbraniecki][:gandalf]]

i don't see any additional problems. 

If this is something different, than for sure description should be more specific. 

Comment 10

[Pascal Chevrel:pascalc]

I also see the problem with pages which use PNG tranparent images like this one :
http://www.macrabbit.com/cssedit/

Remove the PNG image and it scrolls smoothly.

Comment 11

[Max Kanat-Alexander]

That PNG problem might be more closely related to bug 193849, but then again,
this bug might also be related to bug 193849. When that's resolved, we'll be sure.

-M

Comment 12

[Garrett Smith]

Should this be closed? 

We're not supporting -moz-opacity for a while now.

Comment 13

[José Jeria]

(In reply to comment #12)
> Should this be closed? 
> 
No, opacity is still slow

Comment 14

[Wayne Mery (:wsmwk)]

still slow for you?

WFM but very high cpu on a core duo, Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9pre) Gecko/2008040606 Minefield/3.0pre

Comment 15

[martin]

if I tried the reduced testcase with :
Mozilla/5.0 (Windows; U; Windows NT 5.1; fr; rv:1.9) Gecko/2008051206 Firefox/3.0

-> no problem

with : 
Mozilla/5.0 (X11; U; Linux i686; fr; rv:1.9) Gecko/2008051202 Firefox/3.0

-> scrolling the page is VERY slow, totaly unusable, and all the UI became unstable.

So currently it should be a Linux bug.

Comment 16

[martin]

Attachment: more reduced testcase

This a simpler testcase, just a <div style="opacity: 0.5"> with a large text, because the fixed background is not the scope of this bug (and in the previous test, the image is no longer available anyway)

Comment 17

[martin]

finally I have found that my problems with the testcase is specific to my configuration.

Firefox 3 RC1 (original from mozilla), OS Ubuntu 8.04, graphic card NVidia 8400M GS, driver NVidia 169.12 : -> problems described in comment #15

In the same configuration, but with the NVidia drivers removed, and the open source nv drivers : -> absolutly no problems, no lags, very speed and fluid behavior.

So for me it should be a driver bug.

Note that on a french forum, somebody claims he has no problems, with the same firefox, the same OS, the same driver, but a graphic card NVidia 7300.
So my bug is specific to this driver AND this card.

The problem doesn't occur with Firefox 2

Comment 18

[Max Kanat-Alexander]

On F3b5, "A reduced testcase" (my testcase) is still slow on Linux with the stock open-source nv driver. The "more reduced testcase" is not.

Comment 19

[Niklas]

Having the same problem with Firefox 3.0 Release Candidate 1.

If I visit a site that's modifying opacity, my Firefox freezes. Same happens with the addon Sxipper thats using opacity to show a login form. One site I can always reproduce this bug in is http://www.armada.nu. Below is the css part that's making this site freeze my computer:

.transparent{

	-moz-opacity:.80;

	opacity:.80;

}
This CSS freezes my complete ubuntu 8.04 X window (gnome) for about 30 seconds.

The problem does not exist on Firefox 2.x or latest Opera version. Am using Nvidia 8600GTS with driver 169.12. I have also tested with 173.08. If I remove Nvidia drivers, the problem does not exist.

Comment 20

[Niklas]

The problem still exist in Firefox 3.0 Final. I have also tested with the newest Nvidia driver, 177.13, with the same result.

Comment 21

[Siarhei Siamashka]

In order to speed up this testcase, a fast path for OVER compositing operation is needed in XRender/pixman:
SOURCE: a8r8g8b8
MASK: a8, repeat is used
DEST: x8r8g8b8 or r5g6b5 depending on desktop color depth

Comment 22

[Niklas]

Okay, I dont know anything how todo this testcase you have written about above. Am just a end user.
The addon "sxipper" uses opacity (I think) to lower the brightness on a website and only show its own login form bright. This takes 10-30 seconds each time. Under this time, my X is froozen.