1438768 - Writing an email in outlook.com's web-interface is slow

Status: RESOLVED WORKSFORME

(Core :: Layout, defect, P2)

Description

[Clemens Eisserer]

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Firefox/60.0
Build ID: 20180215220507

Steps to reproduce:

Logged into my outlook.com account


Actual results:

Typing an email somehow feels laggy. Characters appear with a small, but noticeable delay - while with other browsers they appear instantly. When I keep the backspace pressed, it seems firefox does not keep up with the key-repeat frequency and deletes a few chars even if the button is no longer pressed.

The WebContent process eats up one core 100% (cust by keeping a key pressed).
Firefox seems to spend a lot of time in ProcessReflowCommands (and childs): https://perfht.ml/2sASenK

Comment 1

[Abe - QA (:Abe_LV)]

Hi Mike,

What do you suggest? The reporter provided the profile. Thanks

Comment 2

[Mike Conley (:mconley) (:⚙️)]

Huh. This is pretty bad behaviour in the profile - we're flushing a ton because of ScrollSelectionIntoViewEvent runnables...

Hey dholbert, you've touched Selection::PostScrollSelectionIntoViewEvent semi-recently... any idea what's going on here?

Comment 3

[Daniel Holbert [:dholbert]]

I don't recall working with ScrollSelectionIntoViewEvent, but I don't know that it's particularly relevant, beyond the fact that it's what triggers the sync reflows here.

I see a lot of nsFlexContainerFrame::Reflow in the stack, so I suspect this is a version of bug 1377253 and bug 1376536 (similar "typing is laggy" issues on Twitter & WhatsApp). Adding dependency.

Bug 1393120 is also filed on other actions (mouseover) being laggy on Outlook -- I'm adding that to "See also".

Comment 4

[Clemens Eisserer]

I wonder - there seem to be tons of reports of high-profile sites beeing slow: WhatsApp-Web, Facebook, Outlook.com and all lead to issues in layout and extensive time spent in reflows. The WhatsApp-Web report I filed is now I guess 6-12 months old and despite the importance of the content nothing happens. Is there a shortage of developers that are understand the layout code?

Comment 5

[Abe - QA (:Abe_LV)]

Based on comment 3, I am putting this under layout component.

Comment 6

[Daniel Holbert [:dholbert]]

Clemens, can you still reproduce? It's possible that some flexbox optimizations over the past year may've helped here.

Comment 7

[Daniel Holbert [:dholbert]]

I tested this myself (at https://outlook.live.com/mail/inbox ) -- I created an email and pasted in lorem ipsum text a number of times until I had ~13000 characters (to have a decent amount of backscroll/content).

Then I started profiling, mashed my keyboard as fast as I could, and stopped profiling.

The text input felt responsive, and my profile is https://perfht.ml/2Xd6Kxp which doesn't show delays and has hardly any time spent in reflow (only ~150ms total, of a nearly 9 second profile)

This is in comparison to the original profile here which showed ~50% of our time spent in reflow (~26 seconds with reflow in the backtrace, out of ~42 seconds' worth of samples).

So, this is WORKSFORME (whether it's our fix or a fix on the Outlook/Hotmail side). Please reopen if you can still see it, though!