USB2 can work at multiple speeds:
Lowspeed=1,5Mbit/s enough to transmit keyboard mouse or joystick data.
Fullspeed=12Mbit/s enough for 4channels at 44,1kHz/24bit + aditional data (midi)
Highspeed=480Mbit/s enough to run multiple digital audio streams in parallel
The actual performance depends on The audio interface itself. Most of USB audio interfaces use Fullspeed, but there is plenty that use highspeed too...