SharePoint Object Model Performance Considerations

Andreas Grabner has posted a brilliant article on performance effects of doing things with the SharePoint object model. He covers which methods you should use over other methods (like using SPContect.Current.List.Items.Count is much slower than SPContext.Current.List.ItemCount), structuring the code etc… and backs it up with performance stats and details on how to do your own.

I would say its a must read for all SharePoint developers.