The Performance Impact Of MDS / Zombieload Plus The Overall Cost Now Of Spectre/Meltdown/L1TF/MDS

One real-world area seeing slightly slower performance following the MDS mitigations is the code compilation speed being slightly slower. Of course, if disabling HT will be an even more profound hit assuming you are building your software with multiple jobs.

Applications mainly sticking to user-space operations don't see any real performance difference with MDS, unless disabling HT where multi-threaded workloads would see a hit.

The Hackbench Linux kernel scheduler benchmark is one of the tests showing the largest impact from the MDS mitigations.

Some of the Glibc micro-benchmarks also a nanosecond or two slower as a result of Zombieload mitigations.