Why do people in old movies move so fast?

First of all, because there are now 24 movies per second, and many old movies are 16 per second, playing at the current speed of 24 movies per second is like fast forwarding.

Secondly, these old films are all old films. If they are stored for a long time, some films will deteriorate and become old, and the fragments will be cut off, so the number of films will be even less.

Therefore, the old films are played at a rate of very few 24 films per second, and an action is played in a shorter time, which is very fast.