The "current stable" version of OMV is 6.0.24, but the newest release is actually 6.3.0-2 and the improvements in the GUI speed that I've experienced are simply stunning! I have a LOT of drives and shares and the GUI used to take a lot of time to build pages but not any more. I'm not sure whether smaller installations will notice the change quite as much, but for me, I'd say that the GUI interface is 3x - 4x faster than it was.
I'm just a user, and not a dev, but I felt like this sort of dramatic improvement merited an announcement, so I decided to post one.