Measurably slower than a LXC container, but still much faster than a full VM.

Not much slower than, say, Hyper-V or Virtualbox or other hypervisors that live alongside a general purpose desktop OS. Remember, they're using the same Intel chips and VT-d and such as anything else; as long as you have enough CPU power it's going to run fine.

IIRC the Docker implementation for OS X runs a tiny, carefully-configured Linux VM transparently in the background. This isn't that dissimilar from the Windows Subsystem for Linux from a user standpoint.

I've done plenty of Docker work on OS X; the only real weirdness is that you're running Linux in the containers and OS X outside. Eventually, though, before switching completely to a native Linux desktop, I moved deeper into the containers and would barely ever see the OS X command prompt any more.

Primarily disk access is a lot slower, even with Hyper-V. Eg. Compilation suffers from this. But tasks that don't use the disk too much shouldn't be that bad.

Our build time on Linux container is 8 minutes, but it's a few hours on macOS using docker containers. I haven't dug into it but the hypervisor seems to be single threading the normally multicore compile.

But doesn’t Docker on Mac run a Linux VM? I don’t think it uses any of MacOS’s isolation features.

Unless you want to run CD to the App Store? So fun....

Ah, but if the XServe had not died and datacenters had racks of these things, there'd no doubt be a production quality implementation by now. Shame.