sway: Sway starts slowly and disturbs shutdown

Whenever I start recent sway versions on my laptop, it freezes during 18 seconds before showing the background (it is normally instantaneous) and htop shows that it in fact consumes the whole 18 seconds of processor time. I can’t even switch TTY during that time, although everything works fine once sway has started.

At shutdown, sway seems to never exit; the TTY from which I try to stop it (be it TTY1 if using shift-mod-e or another one if using kill -15 or kill -9) freezes. I am unable to shut down my system unless I hold the power button pressed for a few seconds.

I confirmed that it happens in 1.0-alpha.6 and 1.0-alpha.5; I did not manage to enable the wlroots experimental flag to build previous 1.0 versions.

I am willing to dive into the code to fix the issue, but I have never contributed to sway so I’ll need some advice to locate the exact version and problem.