The Following Information is Needed to help you
1. Your Version of BitComet
2. Your version of Windows and some basic info about your computer
3. Do you use a Router, What model, and have you properly forwarded your listening port
If your asking a question about a specific torrent or files you downloaded, then be sure to list the full torrents name, as well as the full file names and extensions
For Speed related issues, please run several speedtests from a site like (speedtest.net), making sure no other computers are using your internet connection, and all programs are closed, including bitcomet. Then post the results, along with the settings your currently using, and we will review, and offer suggestions to improve your performance.