Maybe compile LLVM without AVX2 and such fancy things. In config.yml change Use LLVM CPU: "" into Use LLVM CPU: "nehalem" and delete the data folder to force a recompile. This will be slower than compiling for Skylake or whatever you actually have, but it's worth a test. Make sure to change it back for other games.
Asus N55SF, i7-2670QM (~2,8 ghz under typical load), GeForce GT 555M (only OpenGL)