I just recently installed OMV5 on my old machine (which used to run regular debian buster flawlessly).
However, I notice that changing configurations in the web interface and applying them takes an incredibly long time. I'm talking about between 2-5 minutes to apply even simple settings like 'mounting a partition'.
This seems to be universal. It doesn't matter which setting I'm trying to apply. They all take a ridiculous long amount of time to apply