@neobrain of some interest: looking back at screenshots i took of my testing, mangohud reported 0% GPU usage while 40-50% CPU in a mostly idle scene. assuming mangohud is reporting correctly (i.e. actually able to read the GPU usage on the pi), this makes me wonder if the game is actually being CPU rendered? and, in that case, i'm not 100% sure how i can force it onto the GPU, or if the rpi's GPU is even much more capable at rendering half-life ;p