If you don't want to talk to the isp then ... probably not. As the site admin I can check your isp which is Rogers. Rogers is now shaping bandwidth for p2p use, I suspect using a special program that detects p2p programs, which is why your speeds start off ok but then gradually decrease. You could try changing ports but I'm not so sure this will trick such an anti-p2p program. I guess it depends on what ports they're scanning. Try a port somewhere between (49152 - 65535). Go to LW's menu bar, Tools>Options>Advanced>Firewalls & change listening port. If possible also change the other connection port but if you're using upnp then don't worry about that. You may also need to adjust your firewall setting so it allows the new port number.

Other than this would be to try a proxy. A Fix for those whose ISP's block Limewire pages 1 - 3 which have links to alternative instructions. Particularly page 2.