You're not artificially being throttled by Air. That's just the way things are with openvpn with limitations by CPU, network, internet, etc. A client on the usual 1gbit/s server will see only about 500mbit/s download max because the server throughput limit is 1gbit/s inbound and outbound combined.
Air does have at least 1 server that's 10gbit/s. Try it to see if it's any better for you.