If your Act! database does not use the limited access security feature in Act!, then it would be nice to remove the limited access checking from the stored procedures in the backend SQL database. The larger your database gets, the slower it will be. Removing the limited access checking speeds things up quite a bit based on our testing.
If a company decides they need to use limited access, check a box in tools>>preferences>>admin which would then write the code to turn the feature on.