In APID 1.0.48, there is a 'hidden', unsupported feature that allows you to use UndoModes.FAST_ENTIRE_SCRIPT for event processing. UndoModes.FAST_ENTIRE_SCRIPT runs the script in such a way that the whole script either succeeds or does not succeed, and is considered a single undo step.

APID 1.0.48 normally 'wraps' every event into a single undo step - and if the event does a lot to the document, you can get long 'lock-ups' at the end of the event processing - InDesign is doing something with the mass of undo steps it collected during the event processing, and that seems to take a LOT of time in some cases. Let it sit, and it recovers, but it's like a bad hiccup.

By using UndoModes.FAST_ENTIRE_SCRIPT for the event processing, you can avoid most of those delays, but there are some disadvantages.

This new feature is not well tested, but you can give it a go. To enable UndoModes.FAST_ENTIRE_SCRIPT, you need to add a ^ character to your event filter, before the optional script #enginename - like this:

If that character is there, then it will use the fast mode for processing that particular event. E.g.

...,menuSomethingBla^#MyOwnEngine,...