Mozilla VPN uses discrete GPU on MacOS / intel

[noambonnie]

Mozilla VPN uses the discrete GPU on MacOS Intel Macbooks. Tested on MacBook Pro 2018.

The reason this is a problem is that invoking the discrete GPU causes the MacBook hardware to heat up, fans to go off, and battery drain.

I am not familiar enough with the project, but this is likely triggered by some dependency. I've seen on another project that the shift from QT5 to QT6 causes a similar problem.

Since the UX of the VPN is very basic, perhaps there's a way to disable the use of the discrete GPU.

I tested this using gfxCardStatus (https://github.com/codykrieger/gfxCardStatus)

When I quit the VPN:

┆Issue is synchronized with this Jira Task

[noambonnie]

I should note that this happens whether connected to the VPN or not - as long as the app is running.

I should also explain that once the discrete GPU is used, all apps use it, making the problem worse. For example, watching a video or a video call will drain the battery even faster and will render the MacBook extremely hot.

Tested on MacOS Sonoma 14.5

[noambonnie]

Some further info that might be related: https://forum.qt.io/topic/82041/qtquick-forces-the-macbook-pro-to-use-the-discrete-gpu-even-when-the-app-is-supposed-to-use-dynamic-switching/2

[noambonnie]

From Apple developer web site: https://developer.apple.com/library/archive/qa/qa1734/_index.html

[oskirby]

Whatever the cause of this might be, it is not as simple as simply enabling NSSupportsAutomaticGraphicsSwitching - we already set it to True in our Info.plist. And a quick read through of the Qt OpenGL support suggests that it should be configuring the window with the required NSOpenGLPFAAllowOfflineRenderers flag too.