While working with a customer on a PoC we found that the UI workflow becomes slow and eventually crashes the browser prior to completing the intended migration plan. This occurs when using OpenShift 4.15, with MTV 2.5.6 and vCenter 8

We are able to re-create this problem every time in the customers environment, but I have been unable to recreate it with vcsim at this time. 

The customer environment has over 3000 vms in this vcenter.

The slowdown occurs when you get to the vm selection phase of the create migration plan. There are stalls that can last over 3 minutes before the browser becomes responsive again. Eventually the browser crashes and the entire migration plan creation workflow starts over again.