Testing NVIDIA Optimus / DRI PRIME On Ubuntu 14.04
The benchmarking was kicked off with OpenArena, which is one of the least demanding OpenGL Linux games. While the NVIDIA GPU is designed to be the high-performance GPU, in the out-of-the-box Ubuntu 14.04 LTS configuration using the open-source drivers, the NVIDIA GPU performance with DRI PRIME is very bad... The open-source NVIDIA Linux graphics performance remains very poor under Linux due to its lack of dynamic power management / re-clocking. Thus when the NVIDIA GPU is being used in this Zenbook Prime ultrabook, it's stuck to running at very low GPU clock frequencies -- to the extent that Intel HD Graphics 4000 from the Ivy Bridge CPU are multiple times faster.
When switching to the NVIDIA proprietary driver, the GT 620M was running more than five times faster than the Nouveau driver and about 1.5x faster than the Intel Ivy Bridge graphics. When switching to the Intel Linux graphics while the NVIDIA binary blob was present on the system, there was no major change in performance.
The configuration consuming the most power was when using the NVIDIA 331.38 Linux graphics driver on the GeForce GT 620M where the GPU was clocked-up and running for maximum performance. Consuming the least power meanwhile was the Nouveau controlled GT 620M when it was bound to running in its low-power state.