Since speed is a hot topic for our users, we decided to write a post about this and explain how speed levels differ when using a VPN connection and when you are connected to a normal Internet connection.
When using a VPN connection, all data is divided into packets before being sent. These data packets are then encrypted with AES-256 bit. This is a complex and computationally intensive step. After the encryption, more control information is set before the data (Header), so due to additional information every packet is bigger as it originally was. This so-called “Overhead” is proportionally bigger, the more small packages are sent, since the control information have a fixed size regardless of the size of the original packets. For example, at CyberGhost (via OpenVPN) this takes approximately 50 bytes per packet (it varies depending on the setting for encryption, authentication etc.).
The size of the data packets depends, among other things, on the following: over which servers are these sent and which packets size does the remote station accepts (MTU).
At the measurement of speed tests with active VPN connection is measured only how many user data can be transmitted over a period of time, therefore the above-mentioned Overhead is not measured. Read More