To try this, open the file ~/.drirc and add:
<driconf> <device screen="0" driver="i965"> <application name="Default"> <option name="vblank_mode" value="0" /> </application> </device> </driconf>
And then reboot. Right now with this workaround I'm not seeing this problem, but since you said "this behavior starts a couple of minutes after X has started" I will give it some time to see if the bug will come back.
To try this, open the file ~/.drirc and add:
<driconf>
<application name="Default">
</application>
<device screen="0" driver="i965">
<option name="vblank_mode" value="0" />
</device>
</driconf>
And then reboot. Right now with this workaround I'm not seeing this problem, but since you said "this behavior starts a couple of minutes after X has started" I will give it some time to see if the bug will come back.