Comment 5 for bug 561294

I'm running Ubuntu 17.10 with XOrg (Wayland was impossibly laggy).

Every few seconds the window manager will stop updating. Just the mouse keeps on moving, but videos playing will continue.

If I wait a half a minute, it will resume. If I switch to ctrl+alt+f1 and log again, it resumes too.

In the log I see:

Feb 2 14:08:17 fc993847 org.gnome.Shell.desktop[17388]: Window manager warning: last_user_time (332294169) is greater than comparison timestamp (332288825). This most likely represents a buggy client sending inaccurate timestamps in messages such as _NET_ACTIVE_WINDOW. Trying to work around...
Feb 2 14:08:17 fc993847 org.gnome.Shell.desktop[17388]: Window manager warning: 0x4000045 ((39) Why A) appears to be one of the offending windows with a timestamp of 332294169. Working around...
Feb 2 14:09:06 fc993847 org.gnome.Shell.desktop[17388]: Window manager warning: last_user_time (332347345) is greater than comparison timestamp (332338937). This most likely represents a buggy client sending inaccurate timestamps in messages such as _NET_ACTIVE_WINDOW. Trying to work around...
Feb 2 14:09:06 fc993847 org.gnome.Shell.desktop[17388]: Window manager warning: 0x4000045 ((39) Why A) appears to be one of the offending windows with a timestamp of 332347345. Working around...

The name of the offending window varies with whatever I'm focused at the time, doesn't matter what it is.