I am wondering if the rebuild or whatever it's called happens quicker if I have fewer/no dockers and VMs running.  At first they all started when I started the array to start parity rebuild but since then i've shut down most of them.  Does it actually help or should I just leave everything running.  The ETA to complete the rebuild fluctuates a bit but basically says it will be done by late tonight and I started it late last night.

Depends on if they are using the array or not, any array access during a rebuild will cause a slow down, but if the dockers/VMs are for example running on cache and note using the array, or using very little, it will have no impact.