I'm running Maya, and few days ago I enabled the backport repository, and after doing a apt-get install update & upgrade I notice that I there is an awful screen tearing (horizontal as well as vertical) and artefacts (lag, disappearing text, when scrolling up and down) that wasn't there before the upgrade. I'm pretty sure that everything was okay before the upgrade. (I believe the recent firefox 19 upgrade is unrelated to this. I ran it without problems before enabling the backports.) For some reason this is especially noticeable when browsing forums in Firefox, and I also see it a lot in Thunderbird.
So my question is whether or not this is related to enabling backports?