Over the past years a lot of information became available on SharePoint 2007 and the use of large lists. Unfortunately it still happens a lot that large lists are created by users. What impact does this have and how to limit the impact of large lists?
Microsoft recommends to limit view to a maximum of 2000 items. However this is not the only thing that can impact large list performance. When sorting is used in a view, SharePoint has to sort all of the items, before it can create the view. So even when the view only contains 2000 items, SharePoint needs to retrieve ALL items anyway.
Therefore the recommendation for large lists is not only to limit the view to 2000 items, but also prevent sorting as much as possible. Especially in the default view, which is always used when a user accesses the list.