When this happens, do the following:
http://pingtest.net and choose a server in Europe.
If your packet loss is more than 0-1%, you're the one lagging. Packet loss causes a lot of lag for obvious reasons... you're transmitting incomplete data. If your jitter is high, you're the one lagging, it means your ping and connection speed are highly unstable.
Please post your ping test results when making such a topic.