How deterministic is setWatch?

The setWatch() documentation says this, regarding the 'options' field:

// Advanced: If the function supplied is a 'native' function (compiled or assembly)
// setting irq:true will call that function in the interrupt itself
irq : false(default)

Does that mean that the compiled code would NOT be executed by the node event loop?
And as a result, instead of the event being put in an event queue, and possibly held up by other javascript code running, the code would run immediately?

Could that be a better way to handle the pot (as compiled code)?