[ElfBane]

When gaming online, try to have everything on-the-wire. This means corded mouse, keyboard, and broadband connection. Since the BB has to be on wifi, then you will probably always have issues. Since you don't want to spend money, I would cord the mouse and keyboard and see if that helps. If it doesn't help, then money will need to be spent. You can try a router signal booster (Google it). They have some of those things that plug into the wall outlets.
If you don't mind the ugliness, then you can buy the required length of BB cable and then the problem should be fixed. But then there's that ugly cable running down the hall.

As you can see, the goal is to have everything connected by wire if at all possible.

This probably didn't help, but it's the best I can do.