I create my setup.exe's using Burn, and my whatever.msi's using Candle (WiX). I test them on clean virtual machines (Hyper-V, Server 2012, regular 7200 RPM physical disk, differencing "auto-expanding" virtual disk). What I've noticed is that each install takes about an hour on the virtual machine.
But then, I installed it on a real physical machine/real physical hard drive, and it only took a few minutes.
Why is it 10 times slower to install on the virtual machine? Could I be doing something wrong with my VM setup?