Update Network Problem

Hello so i have this:

void Update () {

	if(Input.GetAxis("Vertical") != 0 || Input.GetAxis("Horizontal") != 0){
		MovementDirty = true;


void FixedUpdate() {
	if (MovementDirty) {

		//Send Data//
		MovementDirty = false;

And i wanted to check it directly using the FixedUpdate, but the fps went downtown. But with this way it works. Shouldn’t it be the opposite?

Things which run in Update() run on every rendered frame, things that run in FixedUpdate() runs a set times per second.