I just got a Plugable UGA-2K-A (rev.B) usb 2 display adaptor to enable a third screen on my thinkpad x230 (with “dumb” docking station) and Fedora 18.
Plugging in the adaptor immediately gives me the option of the third screen in display proproties and enabling it works at full resolution, awesome. BUT performance is *atrocious* not only on the displaylink screen but all screens.
First thing I did was test fallback mode, and without 3d accelleration it works great, nice and smooth. Unfortunately I can’t work without gnome-shell (really once you get used to it it’s hard to go back to the old way).
Next thing I tried was disabling hwaccell in an xorg.conf for my HD4000 intel graphics, this forced LLVMpipe gallium driver to be used and it worked fine when the display link adaptor is not active, if i activate the adaptor in the display prefs, all displays power cycle a bit and go dark and the laptop completely locks up (pressing the power button causes a clean reboot however).
At this point, the only way forward I can see is to get displaylink working with the intel chip and both using llvmpipe nicely. Is there any way to acheive this?