Performance issue with code

Hi, I am trying to rotate an object around a center and wrote the following code for this:

 float angle;
 angle = Vector3.SignedAngle(from, to, axis);
 
 void Update(){
         angle += Time.deltaTime * RotationSpeed;
         Vector3 offset = new Vector3(Mathf.Cos(angle) * radius, Mathf.Sin(angle) * radius, 0f);
         transform.position = offset + center;
 }

Since the object is very far from the center however, I run into floating point precision problems, so I decided to let angle be a double instead of a float and wrote the following code:

 double angle;
 angle = CustomSignedAngle(from, to , axis);
 
 void Update(){
          angle += Time.deltaTime * RotationSpeed;
          Vector3 offset = new Vector3((float) Math.Cos(angle) * radius,
                                       (float) Math.Sin(angle) * radius, 0f);
          transform.position = offset + center;
 }

With this implementation I don't have floating point precision issues anymore, but the line: transform.position = offset + center; makes the framerate drop to 2, which I can't understand, since offset is pretty much identical in both cases. Does someone know why this happens?