USB Webcam not working with USB Microphone
I think I found the issue. One of the device is USB 1.1, and this causes the whole hub to fall down to USB 1.1 to accommodate it. I saw it using lsusb -v.

USB 1.1 has a max bandwidth of 12Mbps, hence the reading I get with lsusb -t. I'll need to either replace the USB 1.1 device for a USB 2.0 device, or plug in a second USB card directly in the motherboard.