Convert htaccess to nginx *~EFFICIENTLY~*

Right now they work flawlessly on apache, however I want to convert them to nginx in order to make them more efficient compared to apache. This will be my first step to taking advantage of nginx's event based server and speeding up my system. I understand there is a good and bad way for rewriting url's and I want to make sure they are done strictly for efficiency. I want the fewest amount of if statements as possible. Lightweight. Im looking to do this in the next 2 weeks. The .htaccess file is attached.