The fuck what? This is not even remotely how the Crusher works. It outputs all crushed things AT ONCE, are you sure you are not having the Auto-Output of the Crusher drop Items on the Floor somewhere, making you think it did not produce anything in the first run?
Your measuring must be off in some regard because the mechanics behind the Crusher dont work like you describe them. Please make sure that you actually measure something that is accurate and not dependent on whether you have a valid Inventory to output to or not.
Edit: there is also a TPS Sensor that you can place in World and will show you how many ticks per second your Server is running at all times.