Well, you are right about the assert() call being wasteful. It's going to hit all of the subs that are in the top of your dprofpp output. However, if you really want to speed this up, you need to modify your approach your drastically than just removing that.

What you have here is really a join. Instead of doing multiple fetches, you could do one large fetch, and then construct your objects from it. Basically, I would do one query that pulls back all the columns you need from both tables (you could make this a custom SQL method of a Class::DBI object if you want to), and then feed the results to the construct() method on your classes. See the "QUICK RETRIEVAL" section of the Class::DBI docs for more on this.