Worse performance because ISPs use substandard hardware on both ends to cut costs. Just get a regular router and plug port one into the new router WAN port. If your current modem has wifi then disable it to reduce interference wirelessly. This way here, your modem has to do less work to maintain speeds. My cable modem caps at 95% just with regular browsing and then my speeds tank. It gets quite annoying and if I had the money I would get a new modem.

