16-20ms is not the problem. Your total response time from a screen change to a click getting back to the server is around 250ms (or 400+ms if you have to move the mouse), and I don't believe anybody would be able to see or demonstrate a difference between 10 or 20ms ping.
The problem is that when things aren't perfect on a DOCSIS cable connection then the first thing that goes is often latency - not the minimum or even average values, it's any peaks that you'll notice. Setup a BQM, post a link to a shared graph and we can comment.