Out of 90 benchmarks run comparing the performance hit on this Intel Core i9 9900KS from LKRG, having LKRG enabled led to around a 5% hit based on the geometric mean of all tests carried out. Granted, some real-world workloads like code compilation speed were impacted much more dramatically while test cases not involving I/O or other kernel operations tended to see no measurable difference in run-time performance.

See more benchmarks via OpenBenchmarking.org.