We probably need more details in what you're trying to accomplish. If you're doing this with a database with a large number of product systems, it will take some time to load them all because I think you're asking openLCA to load all the information it can for those product systems. Perhaps what you're trying to do is just get the names or UUIDs of the product systems for further processing. For that I'd use get_descriptors(o.ProductSystem), which will return only names and UUIDs.
