#2 Básicamente es un término para hacer referencia a cómo de natural y estable es la transición entre frames. Si te defiendes en inglés, este post de reddit hace un explicación sencilla con un ejemplo:
Johnny and Amanda take 60 steps over a minute to cross the length of a hallway.
Johnny takes one step per second. Every step would not look much different from one another so his motion is very smooth.
Amanda hops every other step. All the even steps take 1.5 seconds while all the odd steps take 0.5 seconds.
Both Johnny and Amanda are making the same number of steps per minute (frames per second), but the timing per step (frame pacing) differs. Johnny's steps would look very smooth but Amanda's are much more erratic, making the action feel less smooth and jittery.
Un juego en el que se nota bastante, sobre todo al principio en Yharnam, es Bloodborne aunque al cabo de un rato te acabas acostumbrando.