The performance problem has only gotten worse with time. Modern CPUs have a rough time switching tasks. There are all those mitigations for meltdown and spectr

The performance problem has only gotten worse with time. Modern CPUs have a rough time switching tasks. There are all those mitigations for meltdown and spectre. Even before that though, the situation with the TLB was ugly. Limiting your data structures to ones that are friendly to message passing will really hurt you. Hacks to minimize the performance loss add complexity. Fundamentally, glue isn't free. The parts may be simple, but the interactions are not.