Silly author didn't take time to measure on X11, instead 'KDE drops it' author could use older version of KDE or SonicDE fork (rebranded KDE and only X11 support). And while on X11 i'm intresting how XLibre would fare in this metric, because git master of this project feels very snappy.
you do have to appreciate how much time he put into doing all the measurements he did take though