it is a optimized version made by a group of kernel hackers, according to phoronix the stable arch kernel is thr best, it performed better in most situations, so it is the specific use kinda of thing.

if u want want to delve into custom kernels and optimization i think you should try your luck compiling your own kernel, where you can weed out parts you don’t need, apply some optimizations confings and compile to target your cpu exact model