Death by a Thousand Cuts: Small T-SQL Mistakes That Destroy Performance

Many SQL Server performance issues don’t come from one obvious mistake, but from dozens of small, everyday choices in T-SQL code. Over time, these “tiny cuts” add up to slow queries, high CPU usage, and unpredictable performance.

In this session, we’ll examine common T-SQL patterns developers use all the time like implicit conversions, overuse of DISTINCT, scalar functions, unnecessary ORDER BY clauses and demonstrate how each one negatively affects performance. Through clear examples and execution plans, you’ll see why these patterns hurt, how to recognize them quickly, and what better alternatives look like.

Attendees will leave with a practical checklist of high-impact improvements they can apply immediately to write cleaner, faster, and more predictable T-SQL.

Recognize common T-SQL coding patterns that degrade performance, even when the queries appear correct and return the expected results. Understand why small T-SQL choices impact execution plans and resource usage, including CPU, memory, and I/O. Apply simple, high-impact improvements to everyday T-SQL code to make queries faster, more predictable, and easier to maintain.