The driver it still a prototype, although getting closer to release. I am sure there will be optimisations to be found. You should probably follow Eric Anholt's blog, and check out the github page for the driver.
It's worth noting however, that the driver is OpenGL, but the Pi's only have HW to support OpenGLES. Simplistically, that means that when there is an OpenGL function that has no real HW acceleration options, it is emulated in software on the ARM (or perhaps using the quads or the scaler core on the VC4 - not sure). This can cause bottlenecks. So for best speed, you need to avoid those functions. I do not know which functions...Google will though.
Principal Software Engineer at Raspberry Pi (Trading) Ltd.
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