I’ve been using Channels with the Chromecast with Google TV. While the performance has been decent, I have noticed occasional buffering and have found fast-forward and rewind to be a tad sluggish at times, even on Ethernet.
Anyway, I recently discovered one way to significantly improve performance - use a third-party Ethernet adapter. The Google Ethernet adapter is limited to 100MBps, and while that is usually fine for streaming, using rewind and fast forward on video recorded OTA without additional compression can benefit from more speed. I bought a Cable Matters USB-C Ethernet adapter designed for the Chromecast, and now rewind/fast-forward is less sluggish and my speed test shows 350MBps (you don’t get the full gigabit due to the limits of the USB port). Fast-forward and rewind still seem to work better on the Apple TV, but I think that’s a difference in UI rather than performance at this point,
One note - if you go this way, you want to make sure the Chromecast and DVR server are connected by Ethernet to the same router/hub, and make sure neither are connecting to Wi-FI. When I first tried I only got 80MBps, but discovered my Chromecast was connecting to the IP assigned to my DVR computer’s Wi-Fi interface. Also, if you get a more complex USB-C hub rather than just an Ethernet adapter with USB-C power passthrough, you may need another power adapter to supply enough power.