If you were scaled down to the size of an ant the big world around you would be so much slower while ants and other insects of that size would move at normal speed. A human walking would be like a big slow titan.
Is this a kind of physical phenomenon?
There’s two things here, big things do move faster. Horses run faster than insects..
But they don’t accelerate as fast.
There’s a thing called the cube square law that relates lots of things but size and weight are the important one here.
If you double the size of the creature, it’s weight goes up way more than double.
If it grows from one cubic inch to 2:
Size 2×2 is 4
Weight 2x2x2 which is 8
If it grows to 5 cubic inches
Size 5×5 is 25
Weight 5x5x5 which is 125
Bigger sizes even bigger weight increases. Eventually the inertia of the animals body makes super fast acceleration impossible
Yes its physics, there is a reason why Dinosaurs did not grow bigger. With bigger size the leverage effect becomes too strong. Bones would start to weight more as they could support over a more or less fixed size.
There are many reasons i don’t know to be honest, but one more thing i can offer is why spider can not grow bigger as they are. Spider have no Loungs, they use capillary action to breathe, if you raise the size of Capillars they cant work anymore.
in the other direction, there can be no mice that is smart as a human because the brain is too small, you cant make so small (biological) brains with the abilities of a human brain.
I hope that helps even if its not a direct answer to your question
The limbs are moving quickly, what you are looking at are the number of strides per second which due to the extra distance the limbs are moving is a smaller number as the creature gets larger.