Yeah.....I've noticed some delays at times. Sometimes everything seems normal, but sometimes it seems to hang.
Upgrades can be tricky. I used to have to install IOS updates for routers and switches (Cisco mainly) and, the way I look at it, there are 2 kinds of upgrades. First, there are upgrades that are basically fixes (patches) for an existing IOS. Those usually go pretty smooth and don't cause too much trouble because they have been around for awhile and are usually address specific security issues and maybe some add ons. Then you have upgrades that are an entirely new train. The early ones of these can cause unexpected issues because they haven't been as thoroughly tested outside of a lab environment.
From looking at the version, my guess is that this upgrade was of the first type, but am not familiar with Xenforo so maybe this version has some major updates that still need to be worked out rather than minor security patches.
That's a long way of saying I have no idea what the hell is going on and you probably just wasted about 3 minutes of your time reading my post.......