This is in planning, so if I've got the strategy wrong, please let me know. There are multiple questions here, but I think they all degenerate to the same answers.

The hardware is a laptop with a single SSD. I'm trying to not lose the performance of the SSD.

I plan a native dual booting Windows (plus cygwin) and Linux machine which is my BYOD and represents the development environment. I keep the codebase on a shared partition (though sometimes this is an external thunderbolt SSD) which can be natively "mounted" by whichever OS is in operation. I boot into one or the other environments depending on the task in hand. Sometime I have to develop with windows tools, but generally, Linux is my preferred development environment.

It would be ideal if I could VM the other OS and run either in either. I'm going to assume, because I've not found a sensible VM based solution, that I have get samba involved to share the code partition between VMs. Is this going to blow my SSD performance in the VM?

The client also supplies me with a VM for the target environment, usually linux. This is not often suited to development and is used for testing only. I normally keep two copies of this, one as a sandbox and one which I deploy to using the client's preferred method. I keep these VM snapshots on the shared partition.

The latter is interacted with over the network and so has no disk sharing requirements. However, it would be useful for the sandbox to be able to "mount" the code base from the natively running OS. Is this samba or nfs again, depending on the native OS?

Am I missing a trick which allows this to all work smoothly with all four environments running at once without loosing the SSD performance?