Toxiclibs seems to have a fast physics engine. Does anyone know how? (I tried going through the source code myself, but unfortunately I have yet to understand the structure.)
When I manually code physics I use an applyForce method that uses a method I got from Daniel Shiffman's book the Nature of Code (great book) (using PVectors: velocity.add(accel); position.add(velocity); velocity.mult(0);), which is really neat but perhaps there is a faster method?