Since going to Emperor is a plot tunnel without a way back for now, I decided to basically grind out other things.
"the middle kingdom still matters" it says; turns out when you're High Zenith, you can master two dual-town jobs per incarnation... and that's WHEN you're starting the grind, because then catch-up XP bonus becomes more and more relevant, and eventually you can do 3, and then 4... When I had less than 10 left, I could probably just barely fit in a fifth one too, but decided to spend remaining years on wilderness instead.
Doing this, I discovered that some of the dual-town events seem to have part of their body text as title, so you get things like this.
The recent update did increase my speed ceiling to around 1600x in Wilderness and 2400x in some other places. The setup is way too old to ever push 5000x (except maybe whenever I was grinding the beast studies in Hall of Zenith; it was somehow peaking around 3600x there???), but hey, it's something! The minimal UI mode also helps when something's suddenly choking the speed, although it seems to have issues at times maintaining the speed if the game isn't in focus (i.e. its window isn't visible)
As a suggestion, once you are ready for the point of no return in Act 1, perhaps give the player ability to start in the Imperial City to reduce amount of clicks for the clean-ups?