From some browsing through the patches they apply to the packages it appears they are making extensive use of function multi versioning. Instead of compiling for the lowest common denominator for the target arch they are shipping pre-compiled versions for each generation and using run-time detection to figure out which to load.

Nothing stopping any other distro from copying the approach other than detail work and increased package sizes.

Solus did used some clear Linux tuning back in the days when Ikey (founder) was still main Dev. Now the optimizations are still there, but you feel there are getting more rough edges than less, overall. So can't fully recommend Solus OS like I did a year ago :/