I don't really do GPU-intensive stuff on it. It renders webpages & youtube fine, which is probably the most graphical intensive stuff. I'm currently using it mostly for porting MuseScore to arm, mainly using qtcreator for development.

The external hdmi doesn't really work properly...I remember not being able to run external monitor in full screen, or at the same time as the lcd screen.

I just installed and ran glxgears. It gets 250 FPS and a default window size. But I do get an command line error libGL error: unable to load driver: rockchip_dri.so, so I don't think I'm getting GPU.

There is no FOSS lima driver for Mali-T760. There was a lima dev working on it but cause of some e drama that went down the drain.