Remember back when Aerie would suddenly stop walking periodically even when you wanted her to move to a specific destination? What fix was it that, well... fixed the problem?
I can't remember and it seems an npc in my mod is now doing what Aerie used to do.
The most common cause for this problem is the multi-romance script because they're broken and are constantly executing script actions: typically boinging between Active=2 and Active=3.
So when you get a stutter problem with your own code, it means you have a script element that's constantly firing--meaning it's always evaluating as true. Generally it means you forgot to trip a flag from 0 to 1 for that particular block of code (IF DidThis=0 THEN set DidThis=1 do blah blah other stuff.)