Hop on a ladder and you can eat/drink/bandage/etc (anything that plays an animation) instantly.
When you do some action, like eat, it plays an animation. Only once this animation finishes does whatever you're trying to do actually happen. If you're on a ladder or otherwise unable to play an animation, the time it takes to finish an action is the time it takes to get a response from the server.
This can be fixed by disallowing the use of an item that requires an animation when a player is unable to animate, or by enforcing a fixed timer on the use of an item that requires an animation.