Regardless of mass, any Kuiper Belt object with a perihelion equal to Earth's orbit (1 AU) would come zipping in at over 151,000 km/hr (90,000 mph).

Regardless of mass, regardless of how far away it was when it started. It could be a tiny pebble that started out past Pluto, or it could be a 10 km rock that started 10,000 AU out. It would have roughtly the same speed when it reaches 1 AU perihelion from the Sun. If Earth gets in the way, we get whacked.

So, the point I'm making is that we need a new strategy to handle objects that start further out, are not detectable until they are on final approach and have an approximate speed of 90,000 mph.

Because there are bound to be alot more Kuiper belt objects than Asteroid belt objects.