We have used Delphi in Virtualbox for 10+ years using a separate SSD for the VM makes the biggest improvement and using the extensions help, no AV software in the VM. We keep the source on the host drive with a share to the VM, this lets us upgrade the VM/Delphi faster, source control also lives on the host with the source directories excluded from AV monitoring. We run multiple VM's at the same time, 2012 Server with SQL and our services for a complete isolated (virtual networks) production like environment. No need to ever access the internet from the VM's except for Windows updates. We use i7 laptops with 32GB and multiple SSD/M.2's on docking stations with multiple monitors so the Delphi VM has it's own full screen, the 2012 server is minimized 90% of the day.