I doubt very much that any Tomcat settings are causing a significant delay. Assuming the download is managed by the default servlet, it just reads bufferloads of the file and sends packets.
What else is the server doing - how many other users? Can you monitor the server load?
What else is your client side doing - firewall? virus scanner? mutitasking a game?
What else is your internet connection doing? other users?
You'll never get away with this you overconfident blob! The most you will ever get is this tiny ad:
a bit of art, as a gift, the permaculture playing cards