This is true on the face of it, although whether that overhead is significant depends on the number of rows being loaded. I don't consider my loads to be low, although I'm sure there are many processes that feed in a far larger number of rows that mine. If the keys are causing unacceptable slowdowns, then the solution is to disable them during the ETL process and re-enabling them with the WITH CHECK option on completion of the process, not removing them from the design solution. Without them, no matter how good the ETL process is, errors will eventually get in. In addition to the integrity guarentees that this provides, the optimizer can use these keys to produce a better execution plan. Not having them may also require you to turn off the error checking during processing. This was intended to support the development of prototypes. For a production solution this should be considered unacceptable.