Vampiremax:
I think adam7979 misunderstood the question so don't read what he said or it will confuse you further.
Other customers of our VPN in most cases should not affect your speed but other users of your Streamyx internet line (anyone who shares the internet line with you) will be affected if you are downloading at max speed.
This behaviour is not unique to VPN but it's like, let's say you have a 1 mbit connection and you are downloading at max 1 mbit already through VPN that leaves very little for other people in the house who are using the same internet connection.
Just for clarification.
adam7979: your explanation is confusing and implies that our VPN has not enough bandwidth to go around. What Wolffeh is saying is that if your housemate who is using the same line is downloading at max speed, then of course when you use VPN on the same line, you of course won't get max speed cause someone else is using the internet line.