1406706 - firefox cpu spikes on nightly when moving the mouse

Status: NEW

(Core :: Widget: Gtk, defect, P2)

Description

[Stephen]

Attachment: mouse_cpu_about_blank.mp4

User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:58.0) Gecko/20100101 Firefox/58.0
Build ID: 20171007100142

Steps to reproduce:

1. Navigate browser to about:blank to be sure there is nothing listening to mouse events.
2. Open a cpu monitor
3. Wiggle your mouse over the web pane of about blank


Actual results:

Notice cpu spiked to 20% and stayed there as long as I moved my mouse. If I stopped it dropped to 0.


Expected results:

20% usage as I'm moving my mouse around on websites seems high. Especially considering it seems unrelated to the actual web content since my demo reproduced it on about:blank.

Comment 1

[Stephen]

Attachment: flamegraph.png

I ran latest nightly through linux perf and produced a flame graph of what firefox was doing as I moved my mouse around. Hope this helps.