increasing speed

Thirty frames would only be about 1/2 of a second (in a scenario running at normal speeds). It will not take very long for the actor to be going at hyper speeds. To illustrate, after 10 seconds, the actor will be able to traverse a 600-pixel wide world in less than 1/2 of a second. However, if that is what you want, add an int field to count act frames an increment it in the act method. Every time it reaches 30, set it back to zero and increment the speed of the actor.