other methods). If all you're doing is stripping time from a date, then no approach really stands out in my testing. If you're building a date range to pass constants to a query, the one-time convert you do before the query starts is not going to amount to anything in the grand scheme of things. If you're applying the conversion to a column or inside the where clause then it makes more sense to test those scenarios exactly instead of relying on performance tests of independent conversions that have nothing to do with the actual process you're tying to optimize.