Blueprints are quite power hungry…
Hundred+ nodes/variables/functions are already a lot for one blueprint.
In addition, a change often causes “indexing” when other objects using this blueprint are affected. If there are many such dependencies, the problem gets worse.
You need to split the code into separate blueprints (auxiliary objects/components/child classes).
If you “properly” build logic, then the performance problem rarely arises. But if you do everything in one level blueprint, or pawn - in this case, your problem is not in the performance itself…