Optimizing a Drupal database: improving the performance
That is what you have when you don't optimize and maintenance properly your Drupal projects. A 4GB database which hits hugely the server performance. Just a couple of "magic tricks" and .... 194MB.
Magic? Not at all. If you have a problem with your server, with hangs up and things going very sloooow, check the cache. sessions and watchdog tables, and clear them.
It works like a charm :-)