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Investigate increase in First Visual Change and Speed Index for Firefox
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Description

We got alerts almost all over the place for Firefox with our new WebPageReplay setup but when switching between Firefox 70 and 71 but I also did some Firefox preferences changes around that time so I wan't 100% sure that the browser version had any impact.

It looks like this:

However I could see changes for WebPageTest too at the exact moment of the switch. A couple of pages got slower but the Obama page got faster.

I created an upstream issue to ask if they could pinpoint any changes https://bugzilla.mozilla.org/show_bug.cgi?id=1603404

Event Timeline

Peter created this task.Dec 12 2019, 11:19 AM
Restricted Application added a project: Performance-Team. · View Herald TranscriptDec 12 2019, 12:08 PM

I could see the same thing in WebPageTest (this is start render for Facebook):

But not on all pages. The Obama page become faster(!) to render:

Let me create an upstream issue and ask.

Peter updated the task description. (Show Details)

Facebook on WebPageTest and replay for Beijing. Note that there are nog changes for Chrome.

Peter moved this task from Inbox to Doing on the Performance-Team board.Dec 16 2019, 9:04 PM
Peter closed this task as Resolved.Mon, Jan 20, 11:43 AM

This was reported upstream and they could reproduce. Only happens on Linux. However in the next release 72 the performance increased. There's nothing more that we can do about it.