To do a speed test, please open the website SPEEDTEST.NET. Please check at least 3 different servers in 3 different countries and one server in the country you logged in from (in most cases your home country) for getting reliable results.
First do a speed test with your usual Internet connection.
In the upper part you now see the results:
Now connect to a CyberGhost server near you and click on 'test again'.
The result should be near your usual connection speed. If you upload speed rises, it's because of the compression used by a CyberGhost server.
Now repeat the test with three more different servers in different countries and, of course, with the server you have problems with (in case it's not a general speed problem you have).
Note: Please keep in mind the amount of users a server inhabitants at the time testing and the connection distance. Sometimes a crowded server near your location might still be faster than a nearly empty server far away.