bug#42834: 28.0.50; macOS scroll and movement latency slows when display changes

[Alan Third]

On Wed, Aug 12, 2020 at 02:48:08PM -0400, Doug Davis wrote:
> I'm observing this behavior on a MacBook Pro running macOS 10.15
> 
> initial condition: laptop is closed and plugged into an external display
> over thunderbolt; I start and use Emacs with expected performance. After
> unplugging the external display and opening the laptop to use by itself,
> Emacs (which was already running) cursor movement and scrolling latency
> shoots up (Emacs is just very "sluggish"). If I restart Emacs everything
> goes back to normal. I'm observing the same behavior with 'emacs -Q'. I
> don't see the same behavior from Emacs 27.1.

Hi, Thanks for your report, I haven't seen this myself.

Do you see the same thing going the other way? (laptop screen -> monitor)

Is your monitor a retina screen?

NS xwidgets were just added today, did you see this before? (or have
you just tried Emacs 28 for the first time today?)

Thanks!
-- 
Alan Third