If that is the case then either the build up mechanic or the main character's movement speed are extremely out of sync with what is intended unfortunately. Perhaps you are running the game on an unusually fast or slow machine.
Changing the game resolution, using a different browser or switching to the other game version may resolve this kind of issue for all of our games. They usually run at 60 FPS during testing, this should be the ideal frame rate for them to work as intended.