Q: Enable automatic refresh after DDL operations

Does enabling this checkbox invalidate the entire set of cached data about database objects after running a DDL statement? Or does it only affect objects involved in the DDL?

Where is this option buried? I looked briefly and couldn't even find it.

Is this option related to when you create/update/delete triggers/procedures/whatever that may take a moment for SQL Assistant to snap back to life? I seem to remember having a discussion regarding this in the past because I was working on a stored procedure that seemingly kept reverting itself because SQL Editor/SQL Assistant wasn't updating the DDL when I'd go to re-edit the object without a manual refresh.

It's in the top-right corner of DB explorer, next to the Refresh icon. It stops automatic case refresh in the current session until the box is checked again.
Here is a typical use case. You work on updating a view or stored procedure code. You keep updating it and compiling (executing ALTER PROC/VIEW/whatever command), then naturally you want to test the updated version right away executing the procedure , and you don't want to waste time on waiting for SQL Assistant to reload it caches.

Yes, that's the one. It comes in extremely handy when I know I'm going to apply multiple changes to a certain object in rapid succession just to see how it plays and I don't have to turn of DDL refresh for the target database type in SQL Assist, which is more complicated and affects other tabs as well. But does it reload the entire cache or does it only load/refresh the new/updated object? It seems to me it does the former, since it takes seconds for SE to become responsive again. It also puts considerable load ( > 90%) on the cpu during that time.

I'm not certain how it works. From my observations it seems like doing a full refresh of the current database.