[rules-users] What's the performance impact of not flattening object model?

Hi, I understand it may be hard to give a general answer to this question, but maybe you can help me with a rule of thumb? I'm working with a customer that has a business object model that is 3-4 levels deep. A top object with child objects that have child objects and so on... It is fully possible to only insert the top object into working memory and reason over the entire object hierarchy with the help of from, collect, nested accessors etc. But is that not a smart way to go forward? Better to flatten the object model and insert all of the objects into working memory? Will not flattening the object model have a major performance impact? Regards, Mattias Nilsson