ORM performance cost

Question

Does anyone have any experience that indicates what kind of performance hit a developer could expect by choosing to use an ORM (in Django, RoR, SQLAlechemy, etc) over SQL an

Answer 1

It also depends on what you're using as an ORM. In my experience, Hibernate is a pig, in terms of speed, resource usage and startup time. LINQ to SQL, on the other hand, is an extremely light SQL wrapper, whose impact you'd likely barely (if at all) notice.