You didn't say what the time control is where you have a 2000 rating at that other site.
Whatever it is, you can't compare ratings between two different groups of players. 2000 there isn't the same as 2000 here. The rating difference may simply be that so many people play anonymously over there, while they are given ratings over here, which drives down the average rating.
It is interesting that the ping of the Android apps are different. However, 300+ ping for Europeans again sounds like a relative measure. I assume you mean it take 300 milliseconds longer for pings with chess.com than with that other site.
Is that what you mean? What are the actuals? What app are you using to measure the ping?
I love chess.com but android app reacts very slow. It is very slow compared to another site, where I can mantain 2000+ easy. Please do something about it for europeans players, ping is 300+.