Having dealt with run times changing by order of magnitude by removing the mac from equation, it will do so even if there's no overlayfs on the linux VM side.
Corporate insistence on providing ill-fitting developer hardware (Macs) to what our software was being developed on (Linux, and in fact only runnable there) is why they might have paid the cost of few more laptops just for my single EC2 used to have reasonable compile times.
And I wasn't even using the host filesystem for any of the busy path - it was just compile definitions and storage for built tarballs and images (if it had to schlep actual source files and temporary files over, I might have had to wait a week for a single build to finish...)
