Thank you for your feedback. It really helps :)
300 is pretty good!
In fact, the Movement Script uses Time.deltaTime but or more precises time.fixedDeltaTime in the fixed Update but... Had enormous trouble on the build version... i.e. in the editor is have a value of about 30 for speed and in the build version i had to use a 5 times bigger value to even get the character to move :s