Best guess is it's airaccelerate getting changed by the various tron-style maps that have surfing but whatever's causing it something is making the physics of smash maps play out at ~2-3x speed. Blocks fly really fast which is nice but everything else falls or gets knocked over so fast that most maps don't ever get a chance to play out properly.

Personally I'd say somewhere inbetween the current speed and the original speed would be appropriate since before everything fell TOO slowly.