Xanmod is a gaming-optimized kernel… Idk where you read the server stuff from and the performance and the difference isn’t so much in performance… I mean there is still an uplift there but it’s more improved frame consistency (less microstutters) the games just feel more snappy.
Idk what you mean by “low tech computer” but I’ll assume that means “weakest”, I run xanmod on my main desktop PC, which is the only computer I game on, so it only makes sense there. It does tend to kill battery life on laptops and idk anything about getting it to work with nvidia (I’m on AMD). As for the “weakest” computer I’ve ran it on… tbh I don’t remember, I don’t really use a lot of low-end PCs in my daily life.
As for compiling xanmod, no reason to, 90% of the distros either have it in their main repos, or in the AUR on arch or on a copr repo on fedora. I did compile and configure it myself (I use gentoo) but the performance difference between the packaged version of xanmod and the one you compile yourself is minimal, most of the uplift comes from the kernel itself.