Yes, the physics demo shown in the user guide was a bit slow (less than 60fps for sure). This video was made one year before today, using a version of nphysics that was at least 5 times slower than the current one.
Also, unless the gravity is artificially boosted, things may still look a bit slow because of the scale issue described by aaronetz (in all the demos, most objects are around 1 meter tall, and the camera is far enough to see them all). AFAIK, it is not uncommon on e.g. video games, to artificially increase the gravity so that things look a bit more dynamic.
Also, unless the gravity is artificially boosted, things may still look a bit slow because of the scale issue described by aaronetz (in all the demos, most objects are around 1 meter tall, and the camera is far enough to see them all). AFAIK, it is not uncommon on e.g. video games, to artificially increase the gravity so that things look a bit more dynamic.