1440846 - Firefox uses 60% of my CPU while downloading a file

Status: RESOLVED WORKSFORME

(Firefox :: Downloads Panel, defect, P3)

Description

[Cameron Simpson]

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:59.0) Gecko/20100101 Firefox/59.0
Build ID: 20180219114835

Steps to reproduce:

Visit the Calibre download page. Download the latest Calibre DMG for MacOSX. 

https://calibre-ebook.com/download


Actual results:

Observe the CPU spike in my toolbar widget, pop up Activity Monitor, see firefox with 60% of the CPU. Pop up FF's download manager (previously closed). Watch the download finish and the CPU instantly revert to essentially idle.


Expected results:

It should take almost no CPU to maintain a progress bar, and I can't imagine what else is going on. I do have a bunch of extensions, none seems to have any interest in download activity.

Comment 1

[Cameron Simpson]

Some additonal runs suggest this is highly correlated with the amount of progress bar updates (or download chunks received). I have the pleasure of being on a particularly dodgy network right now, which means I got to observe the download vary in speed wildly. When stalled CPU usage was very low, when good CPU usage was very high.

This firefox is running through a local squid proxy, so it is not any kind of direct network interaction.

The download I'm using is about 75MB. The CPU usage exists whether the download manager is visible or not.

Comment 2

[Wayne Mery (:wsmwk)]

The blocker has been fixed - Bug 1562032 - Implement progress bar in the Dock icon in a different way in order to save CPU

Cameron, Do you still see this problem?

Comment 3

[Cameron Simpson]

I no longer see this problem. Thanks for getting back to me! You can close this bug as resolved from my point of view. - Cameron

Comment 4

[Mark Banner (:standard8)]

Closing out per comment 3. Probably fixed by bug 1562032, but I'll mark as WFM.