Load http://redrockbiblecamp.com/cyclathon/ Increase the zoom (cmd-+). Scroll. Very jerky scrolling. A profile says the time is spent drawing the page background image. The page background doesn't appear to be complicated in anyway. Bisected to http://hg.mozilla.org/mozilla-central/rev/2d97da8feb72 using inbound builds.

Is this on a mac? I just tried adding create sampling restricted drawable back and it's still pretty janky on a retina display. It's not any jankier than without CSRD and deleting CSRD should be making background images a lot faster. It's also really slow on Firefox Dev Edition (Gecko 39). I don't think this is a regression from CSRD versus we just always paint background images slowly. I also tried scrolling with APZ and it checkerboards for a few seconds. I'll take a look at it, making background images paint faster is still good.

Yes on a mac. It's definitely a regression from http://hg.mozilla.org/mozilla-central/rev/2d97da8feb72 The difference is night and day for me. Like in the bad case we are talking almost unusable (not "it could be smoothly"). I'm not on a retina screen though. Firefox Dev, Beta and release are all fast for me.

(In reply to Timothy Nikkel (:tn) from comment #2) > "it could be smoothly" "it could be smoother"

And the profiler showed it was under nsDisplayCanvasBackgroundImage, indicating the root background specifically. The other background images were okay.

(In reply to Timothy Nikkel (:tn) from comment #2) > Yes on a mac. It's definitely a regression from > http://hg.mozilla.org/mozilla-central/rev/2d97da8feb72 The difference is > night and day for me. Like in the bad case we are talking almost unusable > (not "it could be smoothly"). I'm not on a retina screen though. Firefox > Dev, Beta and release are all fast for me. Oh wow... hmm. I just tried on my external 27" monitor and it's usable, but not terrible. Both aren't smooth. What kind of external monitor do you have?

(In reply to Mason Chang [:mchang] from comment #5) > Oh wow... hmm. I just tried on my external 27" monitor and it's usable, but > not terrible. Both aren't smooth. What kind of external monitor do you have? It's the same on my external monitor or on my laptop screen (neither is retina).

@mstange: Can you please try the site http://redrockbiblecamp.com/cyclathon/ on your mac and see if it's significantly jankier on nightly versus dev, beta, or release edition? Thanks!

So before with CSRD, we would have a giant image and paint that into one surface with CreateSamplingRestrictedDrawable, then draw each tile. with a portion of the surface. Now we have the image and create an image with a sampling rect and draw that. The performance of a repeated image will depend a lot on the tile size. I wonder if it's better to just create one giant surface, do the repeated image in one big swoop with a call to the native draw target and bypass tiling all together.

Does this bug still reproduce?

Tested on the original machine that I saw this, page scrolls fine now (with and without e10s).