Using a ramdisk/ramdisc - makes my small win10 VM run like lightning!

Might help someone...
I run a small win10 VM (just 13Gb) by using a ramdisk on my imac (with 20Gb RAM) - means small VMs run like lightning!

1. Create ramdisc - type into console...
diskutil erasevolume HFS+ 'RAM Disk' `hdiutil attach -nomount ram://2097152`
(where 2097152 is the size of the ramdisc - in this case 1024*2048*size in ramdisk in Gb - so this example is for a 1Gb ramdisc)
2. Copy VM to ramdisc - but needs to be about 4Gb bigger than the VM)
3. Run from there
4. Don't forget to copy back - if required

Remember this creates a very fragile but very fast VM - good for a v rapid throwaway test VM.)