1329504 - CPU usage spike on Reuters gallery page

Status: NEW

(Core :: CSS Parsing and Computation, defect)

Description

[bug.zilla]

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:52.0) Gecko/20100101 Firefox/52.0
Build ID: 20170108004005

Steps to reproduce:

Visited http://www.reuters.com/news/picture/reuters-30-years-of-pictures?articleId=UKRTR4PGK8



Actual results:

CPU usage spikes to 35%


Expected results:

No CPU spike usage.

Also happens in safe mode:
Tab active: 35% CPU
Tab in background: 8-9%
Tab closed: 1-2%

Comment 1

[Emil Pasca [:emilpasca]]

User Agent:  Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:53.0) Gecko/20100101 Firefox/53.0

I have tested this issue on Windows 10 x64 and Windows 7 x64 with the latest Firefox release (50.1.0) and the latest Nightly (53.0a1-20170110075905) and managed to reproduce it with e10s disabled. However with e10s enabled, the issue is no longer reproducible.

When visiting the specified URL in the description, the CPU usage spikes to 35% and also remains somewhere on ~30% when the tab is active.

I tried getting a cleopatra profile, however I think is something wrong with their server as I cannot upload the report and share it.
I will try again later to see if I can get one.

When testing this issue on Windows 7, the browser hangs and crashes, I've added the crash report:
https://crash-stats.mozilla.com/report/index/969bafdc-14bf-43d7-881a-4302b2170111

Can you please try to attach a cleopatra profile?
https://developer.mozilla.org/en-US/docs/Mozilla/Performance/Profiling_with_the_Built-in_Profiler

Comment 2

[Ciprian Muresan [:cmuresan], Formerly of Ecosystem QA - please needinfo @mcoman for things regarding the team]

User Agent 	Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:54.0) Gecko/20100101 Firefox/54.0
Build ID 	20170124030205

I've taken a cleopatra profile without e10s enabled: https://clptr.io/2ji78W3

And one with e10s enabled: https://clptr.io/2ji5uUF

If the page is in an active tab - 15-20% CPU (e10s enabled/disabled)
If the page is in background - 7-9%(non-e10s) 1-2%(with e10s)

Mike, could you please take a look at the profiles and help us figure out which component should the issue be put in?

Comment 3

[Mike Conley (:mconley) (:⚙️)]

From the profile, it looks like the page is spending a lot of time in JavaScript, inside a jQuery plugin called jquery.mCustomScrollbar.concat.min.js, which I think is "jQuery custom content scrollbar", which has its homepage here: http://manos.malihu.gr/jquery-custom-content-scroller/

That JavaScript looks like it's causing a lot of style calculations to me. So, er, Core :: CSS Parsing and Computation might be the best place.

Comment 4

[Emil Pasca [:emilpasca]]

Thanks Mike.

Comment 5

[bug.zilla]

Attachment: screenshot.PNG

Hi,

was there an update to this?
The issue persists on v.76, but only when the page is in view.

about:performance screenshot attached in safe mode and only two tabs open.

Thanks