This is not the case on Windows and MacOS where there is a significant cost.
That 8 minute spec run, also takes 8 minutes in docker.
https://meta.discourse.org/t/beginners-guide-to-install-disc...
Just use overlayfs and your performance issues are history. Works perfectly on Ubuntu 16.04 and I hope nobody needs to use significantly older systems.
Hah, good one.
Most things are running basically the same when using containers, but not everything. Take networking as an example: That's usually not working as it would on bare metal and usually result in a significant performance loss.
1. is the VM 2. is handling filesystem mounts across operating systems
(2) can be debilitating in dev environments on Mac for example where you want to edit files outside the container but have the container have access to them. Docker have done a lot to improve this over the years but it is still very painful.