How to debug high CPU usage?

[effigies]

xdg-desktop-portal regularly consumes 30-100% of my CPU and occasionally fills RAM until it crashes. I will sometimes find that apps are sluggish to load unless I killall xdg-desktop-portal, which resets it.

According to https://github.com/flatpak/xdg-desktop-portal/wiki/Debugging, using d-feet (or d-spy, which seems to have replaced it) or bustle are the recommended ways to debug, but neither tool is documented, as far as I can see.

I believe that at least one potential culprit is neovim plugins, as I can open a new GNOME session and trigger increased CPU usage by starting neovim, but I don't know what to do to look into this.

I suspect that there's some dbus background that I'm missing that would make these tools legible, but I'm not really sure where to start.

[jadahl]

Run dbus-monitor --session when it's consuming lots of CPU, to see if it gets spammed with method calls.

Run sudo perf record -p $(pidof -x xdg-desktop-portal) when it's consuming CPU, wait for a few seconds and press ^C, then sudo perf report to see where it spent most of the CPU time.

[effigies]

Should I grep for anything in dbus-monitor --session? That generates hundreds of lines per second.

[jadahl]

Grep for interface=org.freedesktop.portal.