The Open-Source NVIDIA "Nouveau" Linux Driver Performance At The End Of 2018
For this benchmarking the testing was obviously limited to OpenGL and for those games that ran stable on Nouveau.
Even with the GTX 680 / GTX 750 Ti / GTX 780 Ti being re-clocked to their highest (0f) performance state, the high-end Kepler cards could barely deliver above a 60 FPS average for the aging BioShock Infinite game. But at least with these cards the performance is multiple times higher than the newer Maxwell and Pascal graphics cards that are stuck to their low boot frequencies.
Dota 2 wasn't playable with any of the tested graphics cards at 1080p when using the open-source driver.
The lightweight ET: Legacy open-source game that continues to evolve the Wolfenstein Enemy Territory experience at least can handle running well on Nouveau... In fact, the newer cards stuck to their boot frequencies could even churn out a 90+ FPS average. For the re-clocked Kepler/Maxwell1 cards, the Nouveau performance comes quite close to the proprietary driver performance.
The OpenArena OpenGL 2.1 era game is another example of something that is at least playable on Nouveau.