The Entity Framework team first published the EF performance considerations whitepaper for EF5 back in April 2012. In May 2014 we updated it to cover and compare EF 4, 5 and 6. We highly encourage people to move up to the latest version of Entity Framework 6 since that's where most of our performance investment is taking place these days.
You can see the entire Entity Framework Performance Considerations whitepaper here: https://aka.ms/efperf
Please leave questions, comments, and requests for improvement in the comments. Thank you!