Maybe "The Art of Theoretical Performance Issue Handling" would be a good title. 😉

Data volume is not the only thing that can change over time (or from DEV environment to PROD). You may have the best query you can create, "in theory", and it can timeout in production where there are concurrent users, lock escalations, I/O bottlenecks, wrong color socks (my theory as to why something works one day and not the next).

I like your list of actions taken. Swearing does seem to help and in theoretical SQL it has been proven not to hurt.

I would add one thing: the click-to-eyeball test. The developer runs the query in Query Analyzer and it takes 1 second. A "really good" developer will run it a few times, clearing the cache each time to get the average of 1 second. At this point one must pronounce it "working good in theory".