I had to drop bit torrent. I began having troubles with it over time. This is why I think I was having trouble. Torrent down loads a file/program more quickly by breaking it into parts, downloading it in sections, then putting it back together. If it doesn't do this correctly then the programs it downloads are flawed. Much like fragmentation over time these damaged programs create problems, slowly at first getting worse over time. I tried other downloaders of similar type and observed the same effect. This is my opinion and I have no facts to back this up other then close observation.
You might contact your ISP and see if they can run some tests on your connect. I have AT&T and have requested that they take a look at my connect on several occasions and they have. They also have a self support tool that can identify problems. If your running Windows your system is equipped with Dr. Watson and other diagnostic trouble shooters that maybe able to identify the problem. And lastly, check your Internet adapter setting. Carefully review the settings and know what they do before you change them. Be careful here or you could loss your connection all together. Of special note is the half and full duplex settings. Changes here can improve your connection but remember it could really screw it up as well. Go slow, your system is still running just not that well.
I'm going to throw this in as well. I recently bought a D-Link network adapter card to replace my chip set adapter. It has really helped increase the responsiveness of my connection but not its speed. I may replace the modem as well. The adapter cost about $30.00. Money well spent.