When you spam-click while using a tool, the durability will drop much quicker than it is supposed to. It also appears to lose durability while the entity is red.

Steps to Recreate:

1. Make a tool or weapon
2. Attack an entity such as a zombie or skeleton (this affects boats and minecarts as well)
3. The durability will drop much quicker than intended

As you can see, the durability will drop incredibly quickly, even with diamond tools.