I frequently read one should use RowLimit on SPQuerys on a large list, especially with more than 2000 items.
An SPQuery object without a value for RowLimit will perform poorly and fail on large lists. Specify a RowLimit between 1 and 2000 and, if necessary, page through the list.
That doesn't make sense to me, as I think it should be "if you have a query with a huge result".
Can someone explain to me why one should use RowLimit even if the query returns no more than about 10 items? (eg on a list with thousand tasks and filtering for open tasks of the current user) Or are all the Best Practices telling wrong informations due to imprecise phrases?