You can uncap the cutscenes FPS from 30, by unchecking the box in graphics settings. Don’t be me and beat ACT IV before noticing.
Also checkout enabling tool tip comparison and advanced tooltips.
And audio effects for loot are really spiffy especially if you use headphones.
There’s also settings to play with toggles for channeled abilities as well.
During cutscenes (and some more cinematic conversation) the quality changes. More lights/shadows go online, possibly model quality gets swapped.
My guess they were worried that computers that barely keep up with 60fps gameplay may have trouble rendering these at full framerate.