This is being caused by a conflict in addons. @Nifty-Chicken will need to report this to the addon authors:
Error: Call to undefined method SV\BookmarkEssentials\XF\Entity\User::canCreateImsSeries()
When? Now? Earlier today? Yesterday?
Everything looks fine for the last 6 hours in terms of what we can see.
I'm in the UK, and everything is loading instantly.