Let every device do what it is best at:
Modem to interface to the line*, a router to manage the network and addresses, a switch to direct traffic around te local network.
A hub does all three and there are compromises - so by getting the switch separate the hub can dedicate more resources to te other functions.
Put ALL devices on the switch, additional latency will be in microseconds or less ad you will not notice. It will ten mean the only traffic on the switch to hub/router is that to/from the internet plus a little management data.
*even on cable there is a line interface through the input port - not a modem but a WAN interface.
M H C
taurus excreta cerebrum vincit