title: Is there a severe performance hit for using Foreign Keys in SQL Server?
body: <p>I'm trying my best to persuade my boss into letting us use foreign keys in our databases - so far without luck.</p>
  
  <p>He claims it costs a significant amount of performance, and says we'll just have jobs to cleanup the invalid references now and then.</p>
  
  <p>Obviously this doesn't work in practice, and the database is flooded with invalid references.</p>
  
  <p>Does anyone know of a comparison, benchmark or similar which proves there's no significant performance hit to using foreign keys? (Which I hope will convince him)</p>