Add Component menu is very slow, when a game object has many sub assets. Could only reproduce this behaviour on Mac 10.6 and 10.7

To reproduce:
- Open the AngryBots demo
- Load the "AngryBots" scene
- In Hierarchy View > select "Environment(static)" object
- Click the Add Component button in Inspector
- Select a component and observe the speed of the menu transitions
- Create a single object in Hierarchy View and click the Add Component button in Inspector
- Observe that the speed is now normal