uTP measures the difference in latency between the smallest latency it has seen to a peer and the current latency. It transfers more or less data to make that difference match a target (100ms).
It uses ping times, and those are connected to the data rate. If it does not seem to be using your entire connection, please run the logging build and post the logs here.
This is actually not due to uTP. This is due to net.calc_overhead being on. uTorrent now actually reports the packet overhead due to ACKs and such. So, you would see this same behaviour if you enabled net.calc_overhead on 1.8.1 with TCP only.
Can you test this again, with no upload or download rate limits? (both set to "Unlimited") I know it seems backward, but it might work, and demonstrate that we can improve something.
Even if you limit uTP down to 5kB/s? It seems unlikely that would have any effect on streaming at all. Let me know where the real threshold seems to be. Also, please run the logging build (13911) and send me the log files.
Please install Debugging Tools for Windows: http://www.microsoft.com/whdc/devtools/debugging/installx86.mspx Then run uTorrent again. When it crashes, post the .dmp file on http://mediafire.com
The UDP tracker spec is insufficient in many ways. The original author is aware, and there is discussion of the new spec here http://forum.bittorrent.org/viewtopic.php?id=18&p=1 When it comes out, uTorrent will look at supporting it.
Going to have to wait for Richard to get back from vacation to fix that. It's not clearing anything, it's that inserting or removing a label causes the selection in the category list to stay where it was, even though it's selecting a new category.