... running a servlet on both sides you'll get the same poor performance ...
You're right, it's slow to use a HTTP servlet. I only mentioned the both-sided-servlet approach because rajit_b said they are currently using a servlet - so why throw it all over when it might not be necessary?
If you want fast response times, you absolutely aren't going to get it with servlets or HTTP for that matter.
You don't have to use HTTP for servlets, the servlet spec lets you implement any protocol, i.e HTTP, FTP, HTTPS and your home brewed protocols if you want. But for fast-paced games, all this servlet stuff is definitely overkill and much too slow.
I'd prefer to implement a custom protocol on top of TCP/IP or UDP if speed is of importance.
PS: Is rajit_b still with us? He's so quite...n