No, I'm not saying that Linq to SQL will replace the SQL Server plan optimization; I'm merely pointing out that a well-optimized (and perhaps dynamic, using reflection) query provider could probably generate better, more efficient SQL queries than 99% of developers in 99% of use cases. You might miss out on some potential optimizations simply because you're trying to get the code working right instead of spending hours to shave a few milliseconds off of your query's execution time (plus, nobody's perfect!)