Or... How I got my server to run OK without wasting too much time.
Database performance, whether in Drupal or any other platform is serious business. There's a lot of benchmarking, analyzing queries, forming hypotheses, making changes, benchmarking again... I've done it and it can take a team weeks to hit performance targets on a major enterprise application. Everyone wants a shortcut. There really are no shortcuts, but sometimes a few tweaks can get you to "good enough".