Your site is being served from dreamhost now. I suspect we must have been getting cached DNS entries a few days ago. (There were two of us above that thought your site was elsewhere.) At the time I even did a traceroute because I was having trouble looking up .vn IP's until I realized.
I watched your site load several times with the Firebug "net" tool activated. You should do the same, you can learn much.
I noticed quite a few images are downloading at one size and scaling down in the browser. Most of those images were not substantially larger than they needed to be in the first place, so the savings from economizing there won't be huge.
I did wonder if your webserver and mysql server are in the same datacenter at dreamhost, you can find that out by inspecting this page in the panel. Dreamhost should automatically assign both the same place, but somehow they don't always catch this problem on there own.