It could be the MySQL quereies, and it could be that your server is heavily loaded, particularly in light of your observation of the loading of your admin panel (which I can’t see or test), but as I said before it could also be connectivity.
Before you start stripping down extensions and modules, there are a few things I suggest you check out:
Run some traceroutes to your site, and compare them with traceroutes to other sites - it could be that you are having issues related to your ISP’s routing to your site, or with latency. I suggest this because your site seems to load well for me.
Try seeing how much loading time is saved without the “off site” trips to your ad networks, by temoporarily disabling them one at a time (particularly the auction ads). It seemed to me that about half the total load time delay was waiting for that data to be retrieved.
Log into your server via ssh and check the load on your server by using the “top” or “w” command - if your numbers are high (on most DreamHost shared servers, much over 10-15), someone on your server might be overly loading the server, and that might be part of the problem.
After that, selectively removing individual extension/modules may point to a particularly “slow” one that could be part of the problem. I just hate to see you go through all of that when the problem could be any of the things, or any combination of the things, listed above.