Optimizing for development and the user experience

Team,

First of all, if you are reading this post, thank you for your consideration,

I am in the process of optimizing my site, http://www.lgsleads.com and have come across a challenge that appears to be insurmountable. While my site, from a visitor or user perspective is loading at an acceptable rate, my admin side load is unbelievably slow! For example, if I want to navigate from the home admin page to the services admin page, it takes at least 20 seconds. As I am sure you are aware this is unacceptable and makes tweaking code/text/graphics a painfully slow process.

Are there any plugins that address this issue specifically? I am using W3 Cache but maybe I am missing how to use it to eliminate this issue.

All recommendations and feedback are appreciated!

Matthew