Networking over hub

I have a 16 port hub connected via uplink port to a 3600 series Cisco switch. The end users are experiencing slow transactions and when I set up continuous pings to the router I would loose ping packets intermitently. There are about 13 connections connected to the hub which connects to a 10/100 TX switch port. Any ideas? I thought splitting users off hub onto a second hub would help but what is the point of a hub if I can’t utilize all the ports? Thanks