21SYSTEM PERFORMANCE AND MONITORING
Even if “it’s slow!” isn’t the most dreaded phrase a system administrator can hear, it’s pretty far up on the list. The user doesn’t know why the system is slow and probably can’t even quantify or qualify the problem any further than that. It just feels slow. Usually there’s no test case, no set of reproducible steps, and nothing particularly wrong. A slowness complaint can cause hours of work as you dig through the system trying to find problems that might or might not even exist.
One phrase is more dreadful still, especially after you’ve invested those hours of work: “it’s still slow.”
An inexperienced sysadmin ...