It's convenient, because you don't need wires. But you pay for that convenience with the following drawbacks:
1) lack of security
2) inherent problems with lag and latency
3) lack of bandwidth
Wireless is what it is and I know of no way to "speed it up".
If you want a fast, reliable network, you go wired. If you want convenience or don't want to pull network cables all over your house, you have to live with the issues inherent to wireless.
If there's some reason you're in a big hurry to transfer these files, buy or make a long enough crossover cable to go from the PC in your bedroom to the one in your living room and connect them with that. Do the file transfer and unplug the cable and pack it away so it's not under foot. You'll find your files transfer a whole lot quicker over a wired connection. Especially if both NIC's are 1000 Mbps.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.