I'm new to Orchard and just started to learn.
One of the most urgent things to know about was how the database storage mechanism functioned and to my great joy, Orchard is not using EF.
Yes... you heard me right. NOT using EF.
I've been on many projects throughout time, tried many different frameworks for data access, and each time we used EF, our projects have gone over time.
EF offers nothing than just complexity, annoying syntax, performance-degradation and so on, seems like no-one anymore is able to write SQL.
I promised myself one thing a while ago, never ever create a project that relies on EF.
And so my journey started in Orchard :)