Thanks for playing and for the feedback!
I did originally include a speed up button that increase the game's timescale, but after using it on a couple of the levels there seemed to be some situations where it would cause a solution that worked at the normal speed to fail. At the time, I looked through the code and couldn't find anything obvious that was timescale dependant and opted to remove it to stop the different behaviour. In hindsight, it may have been better just to keep the option since it was only in one or two places and the speed when retrying seems to have been a bigger frustration!