Just hazarding a guess, but are you using the xiwi X11 replacement? That's just a dummy x server, with everything forwarded to a chrome app. Its a hack to get around the chromeos switch from x to a custom wayland'ish display server. Pretty slow.

But with crouton, you can also run a full xorg on vt-2. And I would be very surprised if anything failed to run there (from a graphical perspective). Even steam with full hardware acceleration works.