we have a plan to optimize our website.
the steps that need to be executed by you are:
1. find good caching solution help off load the db server as it seem the first thing to fail under load (we load balance the app between 5 web servers and all of them are served b y a dedicated db server with redundant resources) like serving cached query result for 3 minutes and then refresh .
2. Combine static images into 1 - 2 sprites
3. optimize images and image size and image output
4. Remove inline CSS/JS