A few comments from an initial glance:
- Site could be improved a lot for mobile. If you get a lot of mobile traffic, which wouldn't surprise me, I'll bet it massively underperforms desktop traffic on site engagement and ad revenue.
- You need to A/B test your ad locations a lot more. The locations do not look particularly good to me, but then again this does depend a lot on how most people interact with your site (which likely isn't starting at the homepage).
- More ad networks isn't always better. Are these ad networks actually outperforming adsense? Are you banned from adsense?
Edit: Ignore these two below, thanks jim-greer. Twitter is in fact hosting the images!
- (ignore) You probably could compress the big images more to save bandwidth. I don't know how big of an expense your edgecast bill is, but I'll bet you could cut it down by a lot.
- (ignore) Additionally, fix the cache headers on your images (change them from max-age: 0 to cache forever -- they look immutable). This will immediately lower your edgecast bill by a little bit and really help performance.