I found out why the Chinese tutorial is so sluggish.

The Chinese tutorial starts off fine, describing the gameplay element of the Garden building. However, when the Immortals are showcased fighting some soldiers and a White Tiger, the battles take forever before the Immortals eventually win. Why is that?

Well, it turns out the player with the Immortals start in the Archaic Age, in which Immortals (as most heroes) start off with the low, low damage value of 1. So despite the enemies health being modified to be lower than usual, a fight would take well near a minute to watch. The only reason the Immortals could win any of them is because their health had been boosted to over a thousand.

As a test, I advanced the player to the Mythic Age, in which the Immortals had exactly 12 Hack attack, and surely, they tore the enemies completely apart.

I'm not sure how such an oversight came to be, but ah well.