If you all actually watch the trailer, you'd realise that it's probably in-universe propaganda. The Jaegers that move quickly and smoothly seem to be concept demonstrations or 3dcg, since when we contrast it with the weightier movements of the Jaeger after blackmemestormtrooper, it becomes apparent that Jaegers still move with weight and momentum.
Looking at that last shot, the jaeger seems faster than the first movie, but the slowness of the fist seems to convey a decent weight, unlike the gundam jaegers earlier in the trailer.
