FixedUpdate and Time.deltaTime slowe

I am moving rigidbodies around with velocity. Is simply using function FixedUpdate(){ thisRigidbody.velocity.x = movement.x; } enough to make the movement framerate INDEPENDENT. versus function FixedUpdate(){ thisRigidbody.velocity.x = movement.x * Time.deltaTime; } Which seems to slowdown my game. Thanks in advance!