c# application flash problem

First, we don't really encourage developers to embed Flash Player in external applications.  If you're making a desktop application based on Flash technology, Adobe AIR is the supported path.

If you've built a web interface to your application and you're actually using a browser running Flash Player as the client and C# on the server side, then it might be worth looking at what browser/os/flash player combinations are involved when people complain. 

Second, it sounds like you need to figure out where the bottleneck is.  You might think about taking a look with Wireshark or Charles to answer some questions for yourself, like:

• Does the client consistently emit requests?
• Does the client consistently emit the right number of requests? (e.g. is it sending duplicates?)
• Does the server respond in expected ways to requests?
• Does the server consistently respond in a timely manner?
• Does the server consistently respond when inside your network, but not when you're outside, or in a particular location (e.g. there's a terrible route between your server and the UK that causes the lag)?

I don't know, there's a million variables and not much in the way of actual information.  Hopefully that gets you started down the right track.

Good luck!

What is FE? How do you communicate with XML?

where your C app is loaded?