The issue does not manifest itself in a VT.
I am definitely not using Wayland. The XDG_SESSION_TYPE env var is set to X11, and the
GNOME doesn't have EGLStreams enabled to make Wayland work with the NVIDIA drivers.
I will test a different DE and/or a live image whenever I have the time. I suspect I might
not be able to reproduce the issue with the default settings, otherwise many other users
would have complained already.
I seem to have quite a few new erros in journalctl compared to what I saw in F25 - many
GTK assertions of different kinds, but none that I can correlate with the lagging
keypresses.
I did just notice that the systemd user sessions is acting in a strange manner. it seems
to always be dying when I log out from GNOME, even when lingering is enabled and/or I have
a second session running. I can't easily find what is causing it to die, other than it
doesn't seem like a crash (`journalctl --user` indicates it was killed by SIGRTMIN+24,
which seems just like the systemd-exit.service unit being called normally).