it’s “Delta” and i think this will definitely solve your problem, look to the “variable timestep” example, you will notice that he multiply the velocity by “delta”,
s.velocity += Gravity.VELOCITY * delta;
s.position += s.velocity * delta;
it’s because in case the framerate changes your speed should also change with it, like that your object is ALWAYS gonna be moving in the same speed, (by same speed i mean that no matter how low the framerate is, the time to travel from point A to point B gonna always be the same)
PS :
it’s one of the most helpful article here (if not the best) you should read it if you didn’t already
i hope it helped, good luck