Im trying to continuously send small UDP-packets (8 byte) as fast as possible from a Samsung Omnia 7 with Windows Phone 7.1 Beta2 refresh (Mango) to a standard PC with Windows 7 and I get very erratic performance.
The weirdest thing is that I get the best performance when sending one message per around 1-4 milliseconds. If I send messages faster (< 1 ms) or slower (> 4 ms) I get strange freezings where the packages seem to get stuck (for 0.5-1 sec every ~0.5 sec) somewhere before they get released again in a burst.
Another weird observation is that the sending phone-app still seem to send the messages continuously. It is as if the freezings arise outside the app, perhaps in the network-device on the phone (?). But why is a 1-4 ms delay between the messages optimal? Why do I get more of these freezings when sending messages with a lower rate (5-50 ms)?
(When sending from the emulator I get good performance.)
Update
Im kind of giving this up for now. Perhaps it works better in the final release of WP7.1. He who waits shall see.
There appears to be an issue with sending UDP data on WP7. See this MS Connect issue log
http://connect.microsoft.com/VisualStudio/feedback/details/690198/poor-udp-performance-in-windows-phone-7-mango