AFAIK, KDE is the heaviest desktop you can run on GNU/Linux. I'd be very surprised if it felt faster than something like Lubuntu; it hasn't been in my experience running KDE on Xubuntu(as an alternate desktop).
The site makes no mention of "optimizations" to the kernel, or anything else relating to speeding up the experience. It looks like an alternative to Kubuntu, based on Debian stable, but with modern kernels backported.
I'm honestly not sure what that gets you. You get Debian stable which is like a rock(but old and crusty), with the newer untested by Debian kernels, which may reduce stability. I guess if something like Kubuntu that isn't Kubuntu appeals to you, it's worth a shot, but I wouldn't do it for performance reasons.