[Tracking Requested - why for this release]: Performance regression on Youtube(at least) Build Identifier: https://hg.mozilla.org/mozilla-central/rev/24763f58772d45279a935790f732d80851924b46 Mozilla/5.0 (Windows NT 10.0; WOW64; rv:51.0) Gecko/20100101 Firefox/51.0 ID:20160823030224 Reproducible: always Steps To Reproduce: 1. Open https://www.youtube.com/channel/UCxVlUVEiwY43qLhCB7kMBIw 2. Try to scroll to bottom with mouse wheel while page is loading ---- Observe: Slow, Laggy and sometimes unresponsive 3. Mouse hover "Popular Upload" and Click [Play All] 4-A-1. Switch to the other applications, so that Nightly is inactive ---- Observe: sound distortion 4-A-2. Click The Nightly taskbar button or right click the button ---- Observe: unresponsive for a while 4-B. Try to scroll with mouse wheel while page is loading ---- Observe: Slow, Laggy and sometimes unresponsive

Regression window: https://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=b6cf6d7a95f993f1b3f656ccaad5445368c85cb2&tochange=183c29790c23279326021e0f6ea6e2c72fb47fc9 Suspect: Bug 1268544

Setting the following preferences seems to fix the problem. user_pref("accessibility.force_disabled", 1);

Are you force-enabling e10s? Are you running with a touch screen?

(In reply to Aaron Klotz [:aklotz] from comment #3) > Are you force-enabling e10s? YES > Are you running with a touch screen? NO Windows10RS1 Home x64 seems to disable e10s by some reason.

Tracking 51+ since this is reproducible and a top site.

I have not been able to reproduce this on my Surface Book. Jim, have you noticed anything when a11y+e10s is force enabled?

The problem(page load is slowu / nresponsive) is not only on youtube but also wikipedia.... https://en.wikipedia.org/wiki/Firefox page load is slow, and become unresponsive while scroll up and down. So, not Audio/Video specific.

Alice0775 White, do you use an IME? I wonder if that needs to be factored into this somehow...

(In reply to Aaron Klotz [:aklotz] from comment #8) > Alice0775 White, do you use an IME? I wonder if that needs to be factored > into this somehow... Yes, I use Japanese IME * Microsoft IME * ATOK2016 <---- default And also I changed Windows10 text size from Contorol panel. 1. Open Control Panel > Appearance and Personalisation > Display (or Start > Settings > System > Display > Advances display settings > Advanced sizing of text and other items) 2. "Change the text size only" "Title Bar", "Menu", "Message boxes" etc. and select all "11"

Alice, any chance this was bug 1295214?

(In reply to Jim Mathies [:jimm] from comment #10) > Alice, any chance this was bug 1295214? I can still reproduce the problem on the latest Nightly51.0a1. https://hg.mozilla.org/mozilla-central/rev/1a5b53a831e5a6c20de1b081c774feb3ff76756c Mozilla/5.0 (Windows NT 10.0; WOW64; rv:51.0) Gecko/20100101 Firefox/51.0 ID:20160829030202

Hi :jimm, The issue still can be seen in nightly, can you help shed some light here?

We'll look at this via our a11y+e10s work.

Alice, ATOK2016 is a third-party IME, correct? Do you know if there is a trial version or something that I would be able to run to attempt to reproduce your problem?

There seems no English page. Sorry Download ATOK2016Trial 30days: 0. http://www.atok.com/try/?w=dl_t 1. After open the page, Please follow attached screenshot

Thanks, I am now downloading it :-)

Hey Alice, are you able to reproduce this on current aurora (51) with e10s on?

Yes, I can still reproduce. On new profile, e10s is disabled(Disabled by accessibility tools) for some reason. Of course, the page load is normal. However, A. When forced to enable e10s, the page load is extremely slow and browser becomes unresponsive for a while(10sec+). <--- this bug B. When forced to enable e10s and disable accessibility, the page load is normal. Tested with STR comment#7 on Aurora51.0a2[1] and Nightly52.0a1[2]. [1] https://hg.mozilla.org/releases/mozilla-aurora/rev/af5a59737002cc4e8bb0f69acddb2583a9d952c6 Mozilla/5.0 (Windows NT 10.0; WOW64; rv:51.0) Gecko/20100101 Firefox/51.0 ID:20161005004013 [2] https://hg.mozilla.org/mozilla-central/rev/ea104eeb14cc54da9a06c3766da63f73117723a0 Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Firefox/52.0 ID:20161005030211

[Tracking Requested - why for this release]:

I can also reproduce the hang on today's Nightly52.0a1[1]. And It is worse than yesterday's build. Taskbar also hang up for a long period. [1] https://hg.mozilla.org/mozilla-central/rev/777fb63db8de8d78b64b8141d1a998397275dd03 Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Firefox/52.0 ID:20161006030208

[Tracking Requested - why for this release]:

We're hoping this will go away with a fix (on another bug) landed in central this morning.

(In reply to David Bolter [:davidb] from comment #22) > We're hoping this will go away with a fix (on another bug) landed in central > this morning. Yep, Seems fixed on Nightly52.0a1. Hope uplift the bunch of patch to 51.0a2.

That's great news! I do plan to attempt uplift. It will be up to release management to approve that, of course...