Yeah, the difference is that this one spawns a prebuilt clang-complete [1] (a more lightweight program) instead of clang. Still, nowhere as good as using a prebuilt ycm_core.so directly. Thanks for the pointer nevertheless.
[1]: https://github.com/Golevka/emacs-clang-complete-async/blob/m...
[1]: https://github.com/Golevka/emacs-clang-complete-async