If you are transferring many small files, expect slower transfer rates than if you are streaming one large file. Also, you might want to try to optimize your TCP stack for a low latency network (basically your LAN acts differently than your usual WAN setup).
There exists a simple program with pre-made settings for exactly this case that is available online here: http://www.speedguide.net/downloads.php
Now if you wanted me to explain to you exactly why this is relevant to your case, I'd only refer you a bunch of technical info which you most likely wouldn't read
So just go download the program and try it out, you might be surprised.