Xresponse is a simple experimental command line tool for measuring UI response times to a mouse click event. It requires the Xtest, to ‘fake’ the mouse event, and XDamage, to report areas of the display that have changed.
For more info see the included README file.
Xresponse is authored by Matthew Allum and Ross Burton. It is free software, available under the GPL.
Xoo is maintained in Git, at http://cgit.freedesktop.org/xorg/app/xresponse/.