|To elaborate a little on the last comment: "Then connect all of your devices to the switch."|
If, say you have a router that is fast enough for the internet but its Ethernet ports are limited to say 100MB/s, if you purchase a switch which is faster, say 1000MB/s and connect it to your router but connect all of your devices to the switch, then the speed between all of your devices will be up to 1000MB/s depending on the devices and cables only with the external (internet) speed the same as they was before. Therefore it is to your advantage to get a switch large enough for all of your devices and connect them all through the switch for the best possible speeds between your devices as possible. Even of you have a Gigabyte router, there still may be some speed advantage to having them all on one switch if possible.
You have to be a little bit crazy to keep you from going insane.