GCC 8 Hasn't Been Performing As Fast As It Should For Skylake With "-march=native"

It turns out that when using GCC 8 since April (or GCC 9 development code) if running on Intel Skylake (or newer architectures like the yet-to-be-out Cannonlake or Icelake) and compile your code with the "-march=native" flag for what should tune for your CPU microarchitecture's full capabilities, that hasn't entirely been the case. A fix is en route that can correct the performance by as much as 60%...