Vaadin IE11 performance

We have an application which is based on vaadin 7.6.2. The performance is fine with IE 11 on my machine in US, but it runs very slow in EU countries on IE 11, and works fine with Chrome and Firefox. Is there any IE settings that I need to check or any other suggestions?

Thanks in advance.

Overall that sounds weird. Only thing I can think of, is that these are completely different kind of connections or computers that people are using. Caching plays of course a big role in intial applucation loading time, but shouldn’t affect after that anymore. Proxies? Do you know, if this is HTTP, HTTPS or Websockets?