Hugh Nougher [:Hughman] Reporter
	Description • 9 years ago

Scrolling, especially using the scrollbar, on the Clockwork Empires website is extremely laggy with e10s enabled.

It is much better with e10s disabled (though not as good as IE11).

For another note the scrolling using mouse wheel is very responsive in e10s but the background and menu lag behind extremely badly.

	Tracy Walker [:tracy]
	Comment 1 • 9 years ago

Hugh, is this reproducible with all of your add-ons disabled?

	Hugh Nougher [:Hughman] Reporter
	Comment 2 • 9 years ago

Just did another test with updated nightly.
Absolutely no difference between a new profile and my normal one.

Also the scrolling response is a little bit better now compared to the other day.
Non e10s is pretty much the same as IE11.
e10s version is still quite horrible.

	Tracy Walker [:tracy]
	Comment 3 • 9 years ago

Hugh, can you try turning off APZ in about:config.

	Mike Conley (:mconley) (:⚙️)
	Comment 4 • 9 years ago

I was able to reproduce, and disabling APZ (by setting layers.async-pan-zoom.enabled to false and restarting) made it better.

Hugh, can you confirm?

	Hugh Nougher [:Hughman] Reporter
	Comment 5 • 9 years ago

Confirmed.

Its smooth with that setting disabled.

	Mike Conley (:mconley) (:⚙️)
	Comment 6 • 9 years ago

Hey - is there an APZ perf bug somewhere?

	Kartikaya Gupta (email:kats@mozilla.staktrace.com)
	Comment 7 • 9 years ago

(In reply to Hugh Nougher [:Hughman] from comment #0)
> Scrolling, especially using the scrollbar, on the Clockwork Empires website
> is extremely laggy with e10s enabled.
> 
> It is much better with e10s disabled (though not as good as IE11).
> 
> For another note the scrolling using mouse wheel is very responsive in e10s
> but the background and menu lag behind extremely badly.

There's two issues here. One is that with APZ enabled and mousewheel scrolling, the background and menu lag. This is because of bug 1166301.

The other is that "scrolling using the scrollbar is laggy" but "scrolling using the mouse wheel is very responsive" - this indicates that the non-APZ codepaths (i.e. dragging the scrollbar) are slow but the APZ codepaths (mouse wheel) are fast.

Since we already have bug 1166301 to track the first issue, let's use this bug to track the second issue.

	Mikel
	Comment 8 • 9 years ago

(In reply to Kartikaya Gupta (email:kats@mozilla.com) from comment #7)
> (In reply to Hugh Nougher [:Hughman] from comment #0)
> > Scrolling, especially using the scrollbar, on the Clockwork Empires website
> > is extremely laggy with e10s enabled.
> > 
> > It is much better with e10s disabled (though not as good as IE11).
> > 
> > For another note the scrolling using mouse wheel is very responsive in e10s
> > but the background and menu lag behind extremely badly.
> 
> There's two issues here. One is that with APZ enabled and mousewheel
> scrolling, the background and menu lag. This is because of bug 1166301.
> 
> The other is that "scrolling using the scrollbar is laggy" but "scrolling
> using the mouse wheel is very responsive" - this indicates that the non-APZ
> codepaths (i.e. dragging the scrollbar) are slow but the APZ codepaths
> (mouse wheel) are fast.
> 
> Since we already have bug 1166301 to track the first issue, let's use this
> bug to track the second issue.

Will this bug also cover enabling auto scrolling via the APZ codepath or should we open up a new one for it?
As auto scrolling on this site is horrific versus the silky smooth mousewheel scrolling which is APZ enabled.

	Kartikaya Gupta (email:kats@mozilla.staktrace.com)
	Comment 9 • 9 years ago

Bug 1105109 covers autoscrolling.

	Botond Ballo [:botond]
	Comment 10 • 9 years ago

(In reply to Kartikaya Gupta (email:kats@mozilla.com) from comment #7)
> (In reply to Hugh Nougher [:Hughman] from comment #0)
> > Scrolling, especially using the scrollbar, on the Clockwork Empires website
> > is extremely laggy with e10s enabled.
> > 
> > It is much better with e10s disabled (though not as good as IE11).
> > 
> > For another note the scrolling using mouse wheel is very responsive in e10s
> > but the background and menu lag behind extremely badly.
> 
> There's two issues here. One is that with APZ enabled and mousewheel
> scrolling, the background and menu lag. This is because of bug 1166301.
> 
> The other is that "scrolling using the scrollbar is laggy" but "scrolling
> using the mouse wheel is very responsive" - this indicates that the non-APZ
> codepaths (i.e. dragging the scrollbar) are slow but the APZ codepaths
> (mouse wheel) are fast.
> 
> Since we already have bug 1166301 to track the first issue, let's use this
> bug to track the second issue.

I tested the page with the patches in bug 1166301 applied. It looks much better, but the background still "lags" a bit - it looks like content is scrolling it slightly in response to scroll events. Not sure if there's anything we can do about that.

	Hugh Nougher [:Hughman] Reporter
	Comment 11 • 9 years ago

Testing this in Nightly now its working very well.
Non-e10s is slightly smoother than e10s but its hardly noticeable.
Thanks for everyone's work.

Is that enough to close this?

	Kartikaya Gupta (email:kats@mozilla.staktrace.com)
	Comment 12 • 9 years ago

Since you filed the bug, if you are happy with the way things are now we can definitely close it. I think there are already other bugs that cover the remaining issues and if not we can file some.