5'8 150 is 22.8 BMI. That's within day-to-day weight variance (can easily vary 3+lbs during the day depending on meal, workout, and pooping timing) of Bryce Hoppel's listed BMI 22.4, calculated from internet listings of about 6'/165lbs. So no, 5'8 150lb isn't too big to run fast. Runners can medal at the World Championship or Olympics at that BMI.