Hi.
I can assure you that they are trying to find a solution.
This issue has been there for a long time, but it did get worst with the latest unity version.
Main issue is unity's design to get things working in the inspector.
Each open component is updated continuously .
For example when you expand a collider in the inspector it will be seen in the scene view and updated.
When you collapse it the collider is not shown in the scene view.
Playmaker holds a lot of data in the backend (not visible) to show every state/action/transitions/colors/names/positioning everything/etc which gets updated all the time when not collapsed.
That is the main Reason fsm with lots of states also tend to slow down.
also, if you have a fsm with many states it will show a note
I actually use many fsms as well on a single object (like player or enemies)
when i need to edit or test some variables from within the inspector and have many fsms, i tend to collapse all.
Then play and expand the one that i want to test values from.
if unity's inspector would be able to expand/collaps component of the same types individually , it could solve already a lot of lag.