No problem, but I hate to be the one to tell you that your site comes up, and operates, fine for me.
The first page completes loading in about 1.5 seconds, and the other pages are maybe 1-3 seconds (which is not at all unusual for zencart.)
I suspect maybe you are having either computer, or ISP issues. What computer OS, and browser, are you using, and what is your connection speed?
Have you run any pings, or traceroutes against your sites? If so, pasting your results into a message may reveal something.
You may also be experiencing a “slowdown” on your computer for any number of reasons as your browser loads, and reloads numerous pages in the admin section.
Does the speed get better immediately after you clear your browser cache and reboot your computer, only to degrade over time while you are using the zencart admin? If so, it is far more likely to be a computer problem on your end than it is with the server.