LAMP Optimization for Database Intensive site

We have a home grown intranet system based on LAMP that has grown with our company over the last 3 years. As we take on more users we are seeing considerable slowness for some of the larger query operations. I put up a test server on AWS with a large configuration to see if that helps and it didn't. I don't think things are configured correctly on the server. I'm looking for an expert to hire on an hourly basis to help me optimize the memory or other configuration parameters for mysql based on the needs of my system. I'm also open to a different server configuration (AWS) based on your feedback. I have a specific page that we can test with - it currently takes about 20 seconds to load on my old server with 1G of memory and about 1 minute to load on my new (test server) with 8 gigs of memory - something isn't right. I'd prefer we chat on skype while you are working on it so i can get you started, give you the credentials, etc. Mike