Wordpress Developer required to optimize site

We're looking for a talented Wordpress developer who can assist us with developing our social learning tool. We are currently experiencing massive problems with the amount of apache calls our site is making, which ultimately results in our server crashing when only a handful of people are accessing the site. It is a Wordpress Multisite installation hosted on a dedicated virtual server with 2gb of RAM.

We need someone who is committed, focussed and knows what they're doing.