You can view the datacenter speed tests here: https://www.digitalocean.com/help/policy/ (Bottom of page)
You can also ping those hostnames through your command prompt or terminal. As with any setup you are describing (Proxy), you should always expect for your internet speed to drop in half for each proxy you go through. I would recommend you upgrade your internet so you don't lag in that game :P (BTW Japanese fan as well).