X3AP: Task management for lasertowers

[Quinch]

So I'm working on a script that will add a bit of fine-tuning to lasertower behavior - and I'm unsure how to go about doing that without creating a massive resource hog. Or, to be precise -

It will run on hundreds, if not thousands of objects {lasertowers, specifically}
Each object will spend most of its time idling
But also, each tower needs to react quickly when an enemy comes into range

Right now, the only way I can think of would be to have each tower constantly check if there's an enemy in range, and act if it's true. However, that creates a sliding scale of CPU vs. reaction - shorter intervals mean more lag, longer intervals mean longer average reaction time.

So my question is, are there alternatives? How does the "Default attack" script they run on normally function when it comes to detection?