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

Performance - its always pro and cons. If you deep deeper into ORM architecture (see my article: avoid ORM bad habits) then you will find intuitively the ways to make it faster. Here's my another article on how to make EF6x 5x faster (at least for read situations): EF6.x 5x faster

Anyhow for good performance, even with ORM you will need to create database views, indexes too as to check the queries that are generated and executed by ORM and fine tune them too. Eager loading is a must with ORM.