Supporting an application as a DBA means you have encountered complaints about performance. The investigation starts and the root cause must be determined. Often times the end result is not a bug in the code but rather something specific to the environment. Environmental problems are usually the culprit.
Performance problems for a SQL Server based application are likely to be caused by environmental factors and not buggy code.
Whether it is a configuration you can change in SQL Server, Windows Server, VMware, or the network it is likely the first course of action is to perform a quick assessment of the environment. This is where understanding the various configurations and best practices are key. Knowing what to look for can save tons of time.
A mistake I often see is a performance issue is passed off to someone else (more senior) and that engineer assumes a lot of things without checking. People are going to relay the problem as they see it – not as it actually is. This leads to skipping over some elementary checks which can save time and frustration from tracking down imaginary bugs.
Start troubleshooting with a quick environmental check.
Below are common environmental mishaps I see when troubleshooting SQL Server performance complaints. Consider these 1st line of action before getting into execution plans, statistics, indexing, and code refactoring.