Currently, VNC has a mechanism to measure the bandwidth (although more or less broken). The bandwidth is presented in the client (F8 -> Connection information). I believe in some cases, it is also printed out by Xvnc. I think it would be useful if latency information is provided as well. On the server side, if we want to avoid spamming xinit.log with such information, perhaps we could add a trigger to print information about this (as well as compression stats etc) upon SIGUSRX.
*** This bug has been marked as a duplicate of bug 7093 ***