Turning off compression can be pretty difficult as you’d be modifying the init.gz script files to stop having it compress, and uncompress the files.
I’ve never had to play with this, but there are a lot of areas in which you’d need to make the modifications. Mind you this wouldn’t affect already uploaded images, and may even make them unusable at that point as you’re no longer having anything that will decompress the files.
I’d recommend giving the system just a few more resources to peck at. Maybe another CPU (3 total if I’m understanding this correct) and maybe limit the amount of hosts able to image at the same time. Defaults usually sit at 10 systems, but you can adjust this under Storage management.
Then play with the number of systems to image at the same time. Maybe lower the numbers. Don’t force systems to image either as it defeats the purpose of the limits you’ve set.
You can, relatively safely, use the VM as that’s how I do all of my testing right now.
Just expect to get the “pinging” of the CPU as it is working pretty hard to keep up. It shouldn’t maintain that level of load for extremely long. I would even, possibly, recommend not having to watch the load average of that CPU as it should be expected, during heavy imaging times, that it is going to be used rather heavily. I even see these on our FOG Dedicated server (4 Xeon 3.2GHz 32GB ram).