If he had pace, he'd be an Mbappe level wonderkid. As a winger, that pace and acceleration gives you that X Factor needed to be a main man and the best in the world potentially. Mbappe had it in spades at Monaco. Messi had that phenomenal acceleration in his young days. Ronaldo had that raw pace. Neymar did too.
Yamal's dribbling is brilliant and his best quality is his agility, balance and flexibility. If he gains weight or muscles, his agility and proprioception will go down. Currently, he reminds me a bit of Mahrez in terms of playing style. Mahrez obviously was a lot more 2 footed naturally.
Lacks the explosive nature and chaotic unpredictability of Dembele's game. He's much smarter than Dembele though. He manipulates the ball brilliantly with his first touch, sudden movements and the weight of his consequent touches on the ball. Yamal definitely isn't a natural finisher/goalscorer though unlike an Ansu Fati for example.
He is not slow though, but I get you. When he goes past his man he can continue the attack and usually they don't catch up. Just that he slows things down due to lack of support.
UEFA.com has his top speed at 32,8km/h, which is slower than both Joao Felix and Pedri
But then they also have Kounde at 33.6, and he was around 31 last season iirc. So it is something that will go up as he is just 16. But never Mbappe or Adeyemi territory obviously.