SQL Server Performance Tuning: Pt. 1 - Page 5

Identifying the Problem

The details from the trace will tell you exactly where your problem is, but you still have to figure out what it is.

The actual process of optimization will be trial and error. You will likely have to run the offending statements several times until you get them right. If your code is essentially a select which doesn't modify data, you can just run it over and over. But if it modifies data you should run it in a transaction/rollback block so you can repeat it:

A simple select:

Select * from authors
  where phone like '408%'

or

exec sp_selectStatement

An updating statement:

begin tran
  go

  update authors
     set phone = 'N/A'
     where phone like '408%'
  go

  rollback
  go

or

begin tran
  go

  exec sp_updatingStatement
  go

  rollback
  go

Use SQL Profiler, Query Analyzer's Show Execution Plan, and/or Statistics IO to see how long each statement is taking paying attention to cpu time.