Intel Ice Lake "0x78" Microcode Update Having Small But Measurable Performance Hits

Indeed, we are seeing numerous small but measurable hits with this new microcode revision. For those not familiar with our testing or the Phoronix Test Suite, all tests are generally run a minimum of three times or more should the standard deviation be too high, among other steps for ensuring statistical accuracy. The number of times run is also displayed on all the benchmark graphics. On the system information tables the CPU microcode version is also always displayed among other transparency efforts in our hardware reviews, etc.

This microcode update isn't causing hits as bad as we've seen from past microcode updates like the JCC Erratum or other security mitigations like KPTI and friends, but does seem to position the Ice Lake performance slightly worse off on this new microcode.