> The first thing window compositors that care about performace do, is use shared memory, then there are a couple of other tricks that don't fit into everything is a file with a stream of bytes.

Then don't use "everything is a file" to do it. I already said that. Use shared memory, I don't care. I'm not talking about implementing anything on Plan9, I'm talking about implementing something new on Linux, instead of implementing Wayland.

> one that can match the performance of existing implementations

pretty easy if we're not talking about Linux anymore. FreeBSD can run Linux programs faster than Linux can, and given Plan9's size, if we wanted to do it there, we could perform even better than that.