Hi Bob,
You can certainly cahnge the value of maxRtmpOutBuffer. It is measured in bytes. I would not recommend 0, but a buffer that can contain a few frames would be fine. So in your case 100 kbps * 3 seconds = 300 kb / 8 = 37.5 KB. The default is 512K, so a change to 30 or 40k would be totally reasonable!
Bryan