Recently I wrote about SQL SERVER – INSERT TOP (N) INTO Table – Using Top with INSERT I mentioned about how TOP works with INSERT. I have mentioned that I will write about the performance in next article. Here is the performance comparison of the two options.
It is clear that performance of the Insert TOP (N) is much better than the INSERT … SELECT TOP (N). However, please note that the result of both of the queries can be very different.
Reference: Pinal Dave (http://blog.SQLAuthority.com)