Syscalls have gotten quite a lot slower after Specter/Meltdown mitigations. Though I suspect that if you're writing a web service that wants TPC you should just disable these - I've told that to Scylla Cloud before, they have no reason to keep them enabled and plenty of reasons to disable them.

The other thing is 'io_uring', which is trying to come at the problem by removing context switching altogether by providing a cheap primitive for communicating with the kernel.