Quote Originally Posted by John Ludlow View Post
Dell, you never actually say it, but you imply that you have had a wired mouse and a USB stick plugged into the same USB3 port - and yet you did not experience any slowdown in access to the USB stick. That is... astonishing to me. My experience is just the opposite, also using USB3.

But my wired mouse is pretty old. I wonder whether some newer wired mice are not USB2 technology now? Maybe that would account for it: a mouse that is capable of running on the faster USB3 stream without forcing it to down shift? This rather than the USB port being backwards compatible by being capable of slowing down for slower hardware.

Of course, the mouse has no need of USB3 speed. But, maybe they have recognized that limiting the circuit to USB2 (or 1) speeds prevents its simultaneous use for other things.
The Mouse is USB 1 or at best USB 2 (nobody is building USB3 mice). The difference is going to be how the physical USB hub is physically wired/structured. USB 3 and USB 1/2 devices utilize different pins on the port, and CAN apparently be structured to segregate the USB 3 and USB 1/2 bandwidth allocations. So depending on how the Hub has be designed will determine how much effect USB 1/2 devices will have on the USB 3 bandwidth.

If a hub is not being used and those devices are being plugged into different USB ports on the computer, than the bandwidth limitations will depend on if the two ports share a common or different USB bus channel.

If they are shared then you will see bandwidth limitations. If they are different, then the two ports operate independently.