DeskRoll Remote Desktop relies on the WebRTC technology to establish direct, peer-to-peer connections between you and your customer/unattended computer. You can check which browsers support WebRTC at http://iswebrtcreadyyet.com/ Peer-to-peer (P2P) means you most surely will get faster connections with a modern browser. However, having a WebRTC-enabled web browser does not guarantee you have a P2P connection. It may depend on the networks infrastrcture, remote computer location, etc.
When you are in a remote session, check the viewport title bar.
Right after the remote host name, there should be a (P2P) suffix. If there is no such suffix, then DeskRoll could not make a p2p connection, so it is using one of its intermediary servers to transfer all the data.