Phoronix published a review on the Linux Gaming Benchmarks With Plasma-Next, KDE Frameworks 5
A quote from the article:
Up for your viewing pleasure today were some quick benchmarks done of the next-generation KDE desktop stack compared to the KDE 4.13.0 and Unity 7.2.1 desktops of Ubuntu 14.04 LTS.Linux Gaming Benchmarks With Plasma-Next, KDE Frameworks 5 @ Phoronix