Consider at the outset of the crisis that this might be a long ordeal that continues through the day and night, and back into day again, for 16, 30, 40, or more hours. No one person, however heroic, should expect to endure, or be expected to endure, for the entire duration. One of my first considerations is who will be available within 8 to 10 hours to take over for me for 8 hours. If you are the most capable person to begin the firefighting effort, then find the next best person to take over from you, and plan on at least an hour of "handover" overlap as well.

Related to a well-defined objective is an actual sample of the key problem area response times. This will become your baseline. A baseline is used for comparison. For example, when someone says, "the query now runs 50% faster," you still want to know if the query runs in 2 seconds or 2 hours. It's similar to a commercial stating something contains "35% less fat!" A statement like that screams for a baseline, and is clearly intent on deceiving and manipulating. Don't fall into the same trap.

If you are not sure what the key business transactions are, then ask your manager. Even better, set up a meeting with the user representatives and ask their priorities. Keep it limited to just a handful of transactions. Let everyone know that initially your team must focus on the absolute business-critical transactions and nothing else. Reassure them that after these transactions are running well, you will move on to another tier of performance analysis.