I think you misunderstood with unsigned. Unsigned does in fact hide your IP, but runescape becomes more laggy, not your computer. In fact, the lag really isn't that bad unless you are botting sw, where you would need to get to the winning team asap so you can get in the game.
Signed uses your IP, but it is as fast as if you were playing on a web browser. I personally bot multiple accounts all using signed, and I have yet to experience a ban/rollback on two characters because of matching IPs. If you can give me your computer specs, I can help you out a little more.