Windows Phone long reaction time

I’m creating a mobile phone phone game. It’s also being released on Android at a later time. The game seems to work pretty good, on computer. When I’m testing the game on my Windows Phone Device via USB, it has a very long reaction time (it lags like crazy). My character is falling down and will move up when pressing the fire key (mouse button click). But for some weird reason the click has a long reaction time. The character (object) doesn’t go up immediately, but a few milliseconds later. It’s very frustrating.

Because I have no clue what is causing this ugly bug, I’ll just paste the code to move the object/character.

 void Update()
        if ( Input.GetButtonDown("Fire1"))
            rigidbody2D.velocity = new Vector2(rigidbody2D.velocity.x, 0);

            rigidbody2D.AddForce(new Vector2(0f, 390));

If you have some profiler running it may cause lag on the gpu, I hear.
Also if you have a lot of code in your touch routine compared to the moment it detects a touch it may seem unresponsive.

Nullrefs and console debug entries will also cause things to slow down. Fix errors and reduce debug output, or use a non-dev build to see what it runs like with that stripped out.

Also, Physics routines, like Rigidbody AddForce should be performed in FixedUpdate() function, not Update() which is framerate dependent.