I'm starting a VirtualBox VM (Windows 7) in a second X-Server (Ubuntu 14.04) and i'm using the following xinit script (/path/.vboximage):

optirun VBoxManage startvm <vm name> &
exec tinywm

I recognized that while running Virtualbox normally under Gnome (Unity to be precise ;-) ) I get full graphics support. But when I run it on a second xserver there seem to be some problems. E.g. Windows Aero doesn't seem to work and Chrome WebGL demos are running with poorer performance. I'm not a big Windows expert, so I don't know how I could check the used Graphic card (specification). But it is very obvious that something has changed when running the vm in the extra X-Server. Also when I try to replace tinywm with compiz I get the unity frame around the VM, which also seems to have no graphics acceleration (no transparency effects) So it seems that the X-Server doesn't have Graphic acceleration at all. I have a NVidia 525m and an Intel HD3000 which are both capable of advanced graphics. I'm starting the above script with startx /path/.vboximage - :1

How could I fix that?