Since the ethernet is on a separate channel, it won't slow down the wifi speed at all. In fact, it might actually improve the wifi speed because you're taking one device off the network thus improving the shared bandwidth for everyone.

Does a wired connection slow down wireless?

The correct answer is that using an ethernet cable instead of using wifi won't slow down the rest of the devices connected to your home network. In fact, the other devices should actually get faster, as there's one less devices using the wireless network.

Do Ethernet cables affect Internet speed?

Your network speed is, of course, separate and unrelated to your Internet connection speed. So, changing out your Ethernet cables may not have an effect on how fast you can load websites because your Internet speed will be almost always pale in comparison to your network speed.