A known concern for supervisory controller synthesis is its scalability. While a supervisor may be synthesized for smaller systems in seconds, for larger and more complex systems this may take considerably more time. Employing the proper techniques for the given situation is essential to mitigate this concern.
Often, rather than synthesizing a single monolithic supervisor, multiple supervisors should be synthesized for different parts of the system, making use of the inherent structure of the system itself. Combining this with abstraction, higher-level supervisors can still be synthesized on top of lower-level supervisors, scaling to very large systems.
Still, multiple syntheses will need to be performed. If you encounter scalability issues for some of them, divide the system further, or resolve the performance problems in another way.