Performance improvements

[nikosmichas]

Hello guys,
Is there any chance to merge #155 and include it in a release?
I was checking some performance issues in my project (using https://github.com/jmcarp/nplusone helped me identify the cause) and some N+1 queries could be resolved with these changes.
If there is something pending in the PR(like tests or anything else) in order to be merged, I would be glad to help.

[frankwiles]

Yep thanks for the reminder! I just merged and released them in 1.9.6.