See whether any of this advice helps.
Reduce the drag caused by LW

To disable ultrapeer capabilities in new versions, tools > options > advanced > performance. While you're there, also disable Mojito DHT capabilities.

If none of that helps, try port forwarding for your router. The instructions are here.
Port Forwarding for the Linksys WRT54G
LW's listening port, port in the 'manual port forward' box & port forwarded within the router config pages should all be the same number