Right now Thunderbird forces the use of the discrete GPU because it uses layers acceleration. OpenGL layers acceleration is probably of minimal utility on Thunderbird, and so it should be disabled.

It's ok for this to be only for OS X, since that's where people are most badly affected by battery-life concerns from using the discrete GPU.

Corresponding Windows bug 667989, general discussion in bug 668552.

Joe can you provide the patch ?

Let's just do it on all platforms.

Mark, review ping?

this setting complicates helping users who may have performance issues unrelated to this setting. So it would be nice to do this soon, and even push it down into version 9 (soon to be beta) (In reply to Siddharth Agarwal [:sid0] from comment #4) > Created attachment 563655 [details] [diff] [review] [diff] [details] [review] > patch > > Let's just do it on all platforms. makes sense, because we have these other bug reports Bug 693852 - High GPU usage with constant status bar animation and direct2d Bug 668552 - Interface is unusable when GPU is busy ... Slow deletes, message viewing, address autocomplete Bug 667989 - DirectWrite/Hardware Acceleration should be disabled by default (direct2d)

Having had a few discussions, we've confirmed that hardware acceleration doesn't have any significant benefit for Thunderbird in its normal use cases. Therefore drivers have agreed to disable hardware acceleration. There is a second preference involved on Windows (gfx.direct2d.disabled) that we want to disable alongside the layers one, so I've updated your patch to include that. This has r+a=me. I'll land these in a bit as I think you're busy at the moment.

Checked in: http://hg.mozilla.org/comm-central/rev/1d249939cafe http://hg.mozilla.org/releases/comm-aurora/rev/786b3e3abd0f http://hg.mozilla.org/releases/comm-beta/rev/2f77787a4916

Great, this may fix a class of problems I was triaging. However, just to be sure, will this disable also Direct2D usage?

It indeed does.

This will lead to Windows users that previously had Directwrite text rendering to have GDI rendering again which might look/behave differently.

bug 689742 comment 0 says the reason is that back then, GL layers triggered the discrete GPU on dual-GPU macs. That's long not been the case anymore. You can safely turn on GL layers, that won't trigger the discrete GPU. What does trigger the discrete GPU is WebGL, and only during the lifetime of any WebGL context.

Yes, this was reverted in bug 950133.