As I don't have enough internal storage space on my MacBook Pro, I used to store my Parallels VMs on an external 500 GB HDD connected via Firewire 800. However, that drive eventually died, and I replaced it with a 3 TB Western Digital NAS.
Now, my Parallels VMs run extremely slowly. Actually, to be more specific – they seem to run at normal speed, but take forever to respond to UI inputs (e.g., when I click a button, there's a 30 to 60-second wait before it responds. But once it does, the UI updates smoothly).
Is there anything I can do to speed up the UI responsiveness, or is this just a side effect of running the VMs off of the NAS?
I run three different Windows VMs (two Windows 7, one Windows 8), and they're all equally slow, so it's not an issue with just one VM. I also haven't changed any settings or anything else other than moving them from the old FW800 HDD to the NAS.