I decided my life was too easy. I’ve replaced Windows 8.1 update with Windows 10 Technical Preview on my primary machine. Overall this works pretty well, but I did run into a performance problem with client Hyper-V.
When setting up a demo virtual machine with Windows 8.1 I noticed it was very slow. I use a Gen-1 machine for the legacy nic, I have a MDT installation in place to install machines like this, so it was more out of habbit than anything else.
Since the performance was miserable, I decided to plug in the ISO and use that one. This wasn’t much faster, so I decided to do the same install with a new VM with Gen-2 as a base. This did the trick. As you can see in the screenshot below, the left machine took almost 27 minutes to come to the same point as the right one did in just over 2 minutes.
So whenever possible… use Gen-2 VM’s.