I was just about to make a thread as well but noticed this has already been brought up as an issue. I wanted to report that I encounter a saw-tooth traffic pattern nearly every time I use BTSync. My image is unlikely to be as useful as the others posted above, but I'm happy to provide more details about my current set up if that is helpful (let me know what you'd like to know/see). The timespan in the image is a five-minute window. My connection is 100mbps down/6mbps up. The tip of the sawtooth appears to often be when the download speed hits the 100mbps mark, and then it appears BTSync backs off by dropping to nothing at all.