Ok, the W3TC options you had enabled for DB Caching and Object Caching were killing the page load times of your site. The DB Caching option seemed to break WordPress transients on your site. This is what was causing those 50 external HTTP requests per page load… 18 of which were hitting my site. The others were to other premium plugins doing their update checks too. Because the results of those requests are saved in WordPress transients and those were broken/not saved every page load would cause the check to happen.
So, I’ve disable those two options and now your admin is more responsive.
The site is still a bit slow but I think a lot of that has to do with the fact you are using so many plugin to try to improve performance that you are actually causing a lot of server load which is slowing down you site over all. Same goes with the security plugins. Those really can cause a performance hit. I would suggest trimming these down.
The CDN still seems to be broken, which means you site is basically broken. I was really tempted to turn the CSN off in W3TC so your site would be fixed but I did not want to make a major change like that without permission.
Thanks for the access and letting me debug why your site was making so many requests to mine!