Just to add an extra voice rather than any answers… 
I have a tiny 1GB DO test site with lots of plugins, so it’s not normally the quickest. However, I think it’s been taking a lot longer recently too, and mine got caught in a weirdness the other day like @MarcP and I had to reset it.
I have never timed it before, but today I set it to ‘Update All’ and made a note of when I clicked the button. So far we have a 9:30 am start, and it’s still going at 10:15. It’s currently bundling some assets. I can say with some confidence that it doesn’t normally take over 45 minutes and counting to do its thing.
Though it looks like it had some permission issues purging temp files? Not sure if that’s relevant.