If you are having speed issues with the VPN connected, the first thing you need to do is to try and quantify the problem and to do this, we recommend that you use a speed test utility, our favourite one is speedtest.net
You can download the Speedtest App from the link below if you don't have it on your iOS device now.
https://itunes.apple.com/us/app/speedtest.net-mobile-speed/id300704847?mt=8
Once installed, please run the speedtest twice, one without the VPN and the other with the VPN connected.
Note: You would have to disable the locations service. On iOS 7 and above, please follow the steps below.
- Go to Settings
- Select Location Services.
- Choose to disable location for every app or just the Speedtest app only.
Once we get these Speedtest results we will be able to assist you further in getting this resolved.