So, in nutshell, I found Lubuntu 14.10 to be the best in performance among the Ubuntu distros. It offered me trouble free experience throughout my usage and I found it to be really stable. Anyone looking for a really really efficient distro and those with low powered machines can safely bet on Lubuntu 14.10
Based on my experience, I found Ubuntu GNOME to be the second best offering very decent performance with a very refined desktop environment. I thought Xubuntu would occupy this position but unfortunately, a bit of instability in the distro marred my experience. I would safely recommend Ubuntu GNOME 14.10 to users with modern laptop with or without touchscreen over the rest of the four distros.
As usual Kubuntu is the slowest of the lot and consumes the most power. You can expect the least battery life from Kubuntu. However, the desktop environment (specially the Plasma 5 upgrade) is mind blowing! Those with powerful modern machines and less usage of battery power can safely choose Kubuntu as it seemed to be the most exciting of the lot.
While I generally don't recommend Nouveau for Linux gaming systems due to the re-clocking still being a huge work-in-progress to allow the graphics cards to effectively operate at their designated clock frequencies / performance states, I decided to run some fresh tests using the Linux 3.18 kernel and Mesa 10.4-devel to see where things stand today. For the tested Kepler graphics cards that support re-clocking, I tested them at their maximum obtained re-clocked frequencies where the system was stable -- generally still below their rated core/memory frequencies.
Unlike the frequency overclocking done through the NVIDIA Settings GUI, the over-volting can only be done via the command-line interface. It's not clear yet if this is just a temporary limitation if NVIDIA didn't get around to exposing it via the GTK interface or they will keep it CLI-only in trying to discourage novice users from accidentally over-volting their system and causing potential damage, etc.
This week NVIDIA introduced the 346 Linux driver beta with a huge amount of changes and new features -- from GPU over-volting to NVENC and VP8 support. Curiosity got the best of me so I've now ran some GeForce GTX 970 and GTX 980 Linux benchmarks to see if the performance of these new, high-end Maxwell GPUs have changed at all with this latest proprietary driver release.
Oded Gabbay of AMD sent out the pull request to David Airlie for trying to land the AMDKFD driver in Linux 3.19. The difference between this driver and AMDGPU is that it's already been public for a while where we're still waiting for the AMDGPU graphics driver to be published that's the new DRM driver to be shared with the Catalyst Linux user-space for supporting the AMD Radeon R9 285 and newer GPUs.
While the AMDKFD driver hasn't yet been pulled by Airlie at the time of writing, this driver has already undergone review from upstream developers and in fact revised six times through the public process. Given that the drm-next merge window is still open for a few more days, this driver stands good chances of being merged then as a new Linux 3.19 driver. Friday's sixth version contains just minor changes to the driver compared to last week.
Intel has sent in another round of graphics driver changes to be queued up in DRM-Next for the Linux 3.19 kernel.
The Intel DRM driver for Linux 3.19 already has initial Intel Skylake graphics support and numerous other changes. Daniel Vetter today sent in yet another drm-next pull request and he says the Intel team will have one more pull request in the coming days once it clears their QA/validation process.
Today's "drm-intel-next-2014-11-07" pull request has Skylake watermark code, reworked audio codec/ELD handling code, Skylake force-wake support, Cherryview support improvements, golden context support for Skylake, and tons of other fixes and improvements.
Find out the full list of these exciting Intel open-source Linux kernel graphics driver improvements via the mailing list pull request. The Linux 3.19 kernel cycle will get underway officially next month once Linux 3.18 has been christened.