The L4 work is usually quoted for relatively recent advances. Presumably monolithic kernels don't benefit from performance work that's specific to micro-kernel

The L4 work is usually quoted for relatively recent advances. Presumably monolithic kernels don't benefit from performance work that's specific to micro-kernel message passing, if performance was all that mattered. I don't remember the OS4000 context switching time but it was fast in comparison with other systems of the 1980s, and it was very fast in actual use (running real-time and interactive processes). The performance of L4Linux is quoted within the typical margin of speculative execution mitigations relative to Linux. However, it's a strange idea to me that speed is all that matters for an OS, and not reliability, trustworthiness, etc.