• Compare the execution plans. Since the queries take so long to run, begin with the estimated execution plan. They will highlight differences between the two servers - say an index exists on one server but not the other. If you're not comfortable with interpreting execution plans, then post them here as .sqlplan attachments.

    “Write the query the simplest way. If through testing it becomes clear that the performance is inadequate, consider alternative query forms.” - Gail Shaw

    For fast, accurate and documented assistance in answering your questions, please read this article.
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    Hidden RBAR: Triangular Joins / The "Numbers" or "Tally" Table: What it is and how it replaces a loop Jeff Moden