I took a look at this specific view. It has 5 projections, 9 joins, 1 union and 2 different aggregations, so I wouldn't say it's very simple. Obviously SAP intended this to be used over a number of Sales Orders, not just a single or handful chosen via input parameter, and obviously it doesn't scale.
Also of note - these are all set to execute in the SQL Engine, I wonder if switching to blank (so that it executes in the Calc engine) has any effect. Why don't you try this out?
Otherwise, I would think about implementing the functionality you need in an Analytic View if you can pull it off.
Regards,
Justin