As part of the upcoming 50+ way Linux GPU comparison on the open-source graphics drivers, I've also been testing the 2D performance for a follow-up article. From that early-on testing I noticed immediately that the Nouveau performance is rather crippled and bottlenecked.
Besides the Intel "Haswell" HD Graphics 4600 from the Core i7 4770K being noticeably faster, the other AMD Radeon results from their open-source graphics driver have also been noticeably faster than all of the Nouveau data... The results in full will come next week.
The performance of all the tested NVIDIA GPUs up to that point delivered roughly the same performance for EXA 2D.
More of these brief 2D performance benchmarks can be found via the 1405261-KH-2DGPUBENC74 result file while the much larger data-set will be done next week. Yesterday I also shared 2D benchmarks from the proprietary AMD and NVIDIA Linux GPU drivers.