yeah, latency is not really determined by usb 1.1, 2, 3 etc. Data thruput would matter in terms of simultaneous tracks in and out, so USB1.1 wouldn't be able to cope with more than 4in/4out, for example. However, PCI or PCIe will be slightly faster in general due to having direct access to the CPU, whereas FW and USB need to go thru a secondary controller. In former days, FW would be faster assuming a good chip (TI) was used,however recently RME,MOTU and M-Audio seem to have manage to bypass the USB controller issue somewhat. more important for latency is well written drivers and the presence of any hidden safety buffers (added to prevent digital conversion problems), and in these areas RME are top dogs.

Ah, I really don't use that much CPU with Sonar, it uses the Harddisk and that is always DMA transfer (USB 2.0 RME) and with PCI-e they do not use the CPU either for graphics anymore, they have their own CPU called a GPU on the graphics card.

getting the bigger picture now.....
just as i thought.

^it made as much sense to you too BB, then...