A Look At The CPU Security Mitigation Costs Three Years After Spectre/Meltdown

Based on all of the tests carried out (all the system details and results available via OpenBenchmarking.org), here is the high-level geometric mean look at the default CPU security mitigation overhead to the selection of processors tested. Again, this is just the default/out-of-the-box mitigation cost compared to booting with "mitigations=off" and isn't even looking at the penalties incurred if disabling SMT/HT out of security concerns - on that front, core scheduling and other initiatives remain a work-in-progress particularly among the data center / cloud operators.

From the tests run for this article, the Core i7 7700K and 8700K were seeing around 75% the performance of the unmitigated (mitigations=off) performance for this up-to-date software stack with Ubuntu 20.10 and the Linux 5.10 LTS kernel. With the hardware mitigations incorporated into newer Intel CPU designs, with the current generation Intel Core i9 10900K with the same benchmarks is now at just over 95% the unmitigated performance. On the AMD side, with the new Ryzen 9 5950X it's about 90% the unmitigated performance due to the enhanced Zen 3 protections increasing their overhead -- but fortunately the new AMD Zen 3 CPUs are super speedy and so the numbers everyone are used to seeing are of that default mitigated performance on Windows and Linux, compared to the slowdown existing CPU users saw in January 2018 after the fact when these mitigations initially came to light.

So now three years to the day later, that's currently how things stand at least until any further software improvements are made or new CPU security vulnerabilities brought to light.