bug#62975: 29.0.90; Forking processes on macOS has become very slow in Emacs 29

[Eli Zaretskii]

> Date: Sat, 22 Apr 2023 07:06:17 +0000
> From: "M. Ian Graham" <hello+emacs@miangraham.com>
> 
> > Can someone else who uses Emacs 29 on macOS reproduce this regression
> > in performance relative to Emacs 28?
> 
> I've observed the same general trend at the same general time but had trouble 
> getting a clear handle on the difference.
> 
> Vague personal observations: I've noticed slowdown on macos (x86) but not 
> linux in recent months, but in addition to moving emacs versions from v28 to 
> master to v29 I've also changed installation methods from homebrew to 
> nix+home-manager so that's a massive confounder.
> 
> Large loads of things like my org config, elfeed or magit seem sluggish now 
> (often multiple seconds) where they were snappy before (sub-second), and my 
> impression has been that either forking or I/O is much slower but I haven't 
> done much narrowing. I'm unsure at present whether my own observations are 
> due to emacs versions or nix/build/installation differences.
> 
> On magit specifically, I've followed the magit manual's advice re: the magit 
> executable affecting perf 
> (https://magit.vc/manual/magit/MacOS-Performance.html) but not seen 
> significant changes there.
> 
> I just attempted to reproduce some difference via emacs -Q and a simple 
> recipe, but haven't easily been able to see a signal. Below are my results 
> for v28 vs v29, both installed via nix. I'm also slowly trying other 
> installation methods with the same recipe to see if anything jumps out.
> 
> So far, v28 feels plenty slow too.

Thanks.

To be useful, these observations should include invocation of other
programs, not just of Git.