bug#39790: 26.3; Painting text on macOS has becoming unbearably slow

[Alan Third]

On Tue, Feb 25, 2020 at 10:39:36AM -0800, John Wiegley wrote:
> I use Emacs master as a dedicated ERC application window on macOS 10.15
> (Catalina).
> 
> I've found that with current master (at least, up to the commit before the "no
> text" bug I reported earlier), text redisplays *very very* slowly. In fact, I
> can type faster than Emacs can display letters to me, hearkening back to ye
> olde days of 110 baud modems.

Some stupid questions:

Are you using a transparent background?

What sort of hardware are you using?

Can you send me the first block of info report-emacs-bug puts in the
bug report, that looks like this:

In GNU Emacs 28.0.50 (build 192, x86_64-apple-darwin18.7.0, NS appkit-1671.60 
Version 10.14.6 (Build 18G3020))
 of 2020-02-25 built on breton.holly.idiocy.org
Repository revision: 4b118bdca1d8aa130fb67eadb16e08e87e698aa4
Repository branch: master
Windowing system distributor 'Apple', version 10.3.1671
System Description:  Mac OS X 10.14.6

-- 
Alan Third