The problem I'm observing is well described at
https://forum.antergos.com/topic/9533/key-repeats-and-an-unresponsive-wayland .

On a fresh TW installation with Wayland, the desktop briefly freezes during
typing and when it comes back the last character is repeated many times. This
is not isolated to a single application. I've seen this behavior with
VirtualBox, Chromium, GNOME Terminal and GVim. TTTTTTTTThe system log is
filling with messages like this:
Nov 29 17:16:33 fmn org.gnome.Shell.desktop[1914]: Key repeat discarded,
Wayland compositor doesn't seem to be processing events fast enough!
Nov 29 17:16:33 fmn org.gnome.Shell.desktop[1914]: Key repeat discarded,
Wayland compositor doesn't seem to be processing events fast enough!
Nov 29 17:16:33 fmn org.gnome.Shell.desktop[1914]: libinput error: client bug:
timer event1 keyboard: offset negative (-372ms)
Nov 29 17:16:33 fmn org.gnome.Shell.desktop[1914]: Window manager warning:
last_user_time (251082637) is greater than comparison timestamp (251082073). 
This most likely represents a buggy client sending inaccurate timestamps in
messages such as _NET_ACTIVE_WINDOW.  Trying to work around...
Nov 29 17:16:33 fmn org.gnome.Shell.desktop[1914]: Window manager warning:
0x2000001 (Enter Bug:) appears to be one of the offending windows with a
timestamp of 251082637.  Working around...

Hardware is Lenovo X260. More details can be provided upon request.