bug#42406: macOS metal rendering engine in mac port

[Aaron Jensen]

On Fri, May 21, 2021 at 3:23 AM Konrad Podczeck
<konrad.podczeck@univie.ac.at> wrote:
>
> Aaron,
>
> could you please also look on the performance of wheel-mouse scrolling in all 
> the scenarios below, to see whether it makes a difference:

I can't really feel much of a difference with wheel mouse scrolling.
Trackpad scrolling has a significant difference however, with NS port
being the winner regardless of frame size. Metal feels slightly more
sluggish than non-metal macport.

Disabling mac-mouse-wheel-smooth-scroll on macport helps immensely and
I'd say macport without metal feels slightly better than NS when that
is disabled metal feels similar or slightly worse to NS.

And in all cases a smaller screen makes it feel more smooth, but the
stack ranking remains the same.

Not super scientific, but hopefully helpful.