[sergiolp]

Communication would've happened, but probably between far less actors. So, you have a communication channel which is orders of magnitude slower, and bigger communication needs. Not good.

That said, about the reliability point, I agree with you. If you're building an specialized system, and reliability is your main concern, microkernels+multiservers are the way to go (or, perhaps, virtualization with hardware extensions, but this is a pretty new technology for some industries).

Probably you're going to need to add orthogonal persistence to the mix, to be able to properly recover from a server failure, or an alternative way to sync states, which will also have an impact on performance. But again, you're gaining reliability in exchange.

[nickpsecurity]

The communication channel does get slower. The good news is that applications are often I/O bound: lots of comms can happen between such activity if designed for that. One trick used in the 90's was to modify a processor to greatly reduce both context switching and message passing overhead. A similar thing could be done today.

Of course, if one can modify a CPU, I'd modify it to eliminate the need for message-passing microkernels. :)