I may upgrade the cache drive to a tb nvme and see if that works better. I'd lose redundancy but it might run better...
Discussion
A faster drive will help for sure. I've got everything on sata SSD.
I would but my tb nvme is in my other PC. Unfortunately, the way Unraid works means the nvme has no form of backup, only the array drives do. So I choose speed or data redundancy... the cache drive is 256gb and being used by all the docker containers as well.
As a quick test I am bumping the virtual ram to 8gb to see if it helps too.
Okay... that was the problem... the VM needed 8gb. Umbrel loads almost immediately now.