OK, let's step back a bit here.
How fast your torrent will download is influenced by many things. Obviously this may include the speed of your internet connection. The fact that you're on wireless may also introduce some lag since wireless b/g networks are often slower than their wired counterparts.
However, by far the slowest link in the chain is the number, and your connection speed to, the other people who are seeding the torrent. The whole concept of a torrent download is that a bunch of people are feeding off each other, "trading" data that you have for what you need. The more people, on faster pipes, the more gets traded, and the faster it all comes in. If, in an extreme example, the only two people on the planet interested in downloading a file are you and another guy on a dial-up connection in South Africa, well, your download speed from him is going to stink.
So the question to ask is: What's the rest of your internet connection like? Is surfing the web and downloading from websites just as slow? If not, then your connection speed is not your problem, it's all to do with the number of people seeding/downloading the particular file you're after.
I've seen the same torrents go from 10 bytes/sec to 500KB/sec, all depending on the time of day, what the file is and how popular it is, etc.
(And, frankly, I'm not sure what port forwarding has to do with any of this. If the ports aren't being opened, the download wouldn't work at all, not just be kinda slow... right?)