A wait time of zero would mean that the system will dispatch all events immediately to Automagic which will likely slow down the entire system a bit since. Not sure if this is noticeable from a battery point of view.The timeout after the most recent event of a given type before an AccessibilityService is notified.
Note: The event notification timeout is useful to avoid propagating events to the client too frequently since this is accomplished via an expensive interprocess call. One can think of the timeout as a criteria to determine when event generation has settled down.
The measured time on my main test device between starting settings and detecting settings is about 200-250ms. The time when the system notifies Automagic about the settings screen and invoking the script that measures the time is about 60ms so most of the measured time (on my device) seems to be between starting the settings activity and the system notifying Automagic about the new foreground app (about 160ms). I don't see much space to improve this at the moment.