Check performance of drupal websites using some modules or tools
You could try new relic, it will give you insight into how expensive database queries are or where you have a bottle neck which is slowing down your site. It has some integration with Drupal and could also show you if you have a problematic module...

Also if your pages use a lot of views, have you tried caching the views? It is part of default views module, go into your view edit under "advanced" on the right. Click caching and turn this to time based. This means that rather than running each view query / view rendering on every page load - It will run it on the first load and retrieve a cache until it expires. The caveat here is that you will have a lag on the results for how ever long you choose to cache.