Unity web player slow response to first interaction

It freezes for a long time. On a mac I even get the spinning pinwheel cursor. When running the profiler in the editor I get a spike on button press (Canvas.SendWillRenderCanvases using most of the resources), but it quickly drops back to regular frame rate.

Ok I see what you meant. On clicked the button calls this method in the UI manager:

 public void LeftButtonPressed() {
         ChangeForgeState (forgeState.cardSelect);
         leftButton$$anonymous$$enu.GetComponent<Forge_$$anonymous$$enu_Appear> ().Open$$anonymous$$enu ();
     }

the 'ChangeForgeState' method just activates and deactivates some UI elements:

 void ChangeForgeState ( forgeState _newState) 
     {
         switch (_newState) {
         case forgeState.cardSelect:
             buttonLeft.SetActive(false);
             buttonRight.SetActive(false);
             buttonTop.SetActive(false);
 
             break;
         case forgeState.forge:
             buttonLeft.SetActive(true);
             buttonRight.SetActive(true);
             buttonTop.SetActive(true);
 
             break;
         }
     }

meanwhile the menu appear has a small animation for the menu to appear:

 public void Open$$anonymous$$enu () {
     gameObject.SetActive (true);
     StartCoroutine(transform.$$anonymous$$oveTo (targetLocation.localPosition, animationDuration, Ease.QuadInOut));
     StartCoroutine(transform.ScaleTo (Vector3.one * targetScale, animationDuration, Ease.QuadInOut));
 }

($$anonymous$$oveTo and ScaleTo are tweening methods from the Automotion plug-in)

The menu that appears contains one panel and 10 buttons, but none have any special code on being enabled.