It depends on how the spawning works, if they spawn in at static locations then yeah going as fast as possible is best because you'll have a greater chance to aggro one. On the other hand, if it's a event or spawn that happens when you are in the right circumstances (night/storm, in an ocean biome) then going slower is more convenient. After doing quite a bit of hunting for them, I'm going to guess it's probably static and faster is better.