Originally Posted by TeraTask

Oh, yes. Optimization can be extremely important. I once wrote a program which took a collection of ratings from users and converted those into recommendations. There were 100's of users, 1000's of ratings, and 1000's of videos (which they were rating). The process of creating a recommendation was so intensive that it caused the server to stop for a few hours while all the processing took place. Optimizing that code (by precaching certain results) reduced the work down quite a bit, but it ultimately had to be done on a separate box.