I do the same of not using Bridge mode and find it makes little or no difference to the internet speed of the devices connected through my Dlink router. Now I have the unused Ethernet ports in the Hitron CODA4582 for other purposes.
I have the same issue with my D-Link DIR-868L router connected to the CODA-4582 modem. I found no difference in speed between bridged mode and gateway mode.
