[LAU] Freebob high CPU usage

Hello, I have two computers (desktop and laptop) with Ubuntu Hardy (using kernel RT on both) and a Edirol FA-101 firewire interface. I was comparing Jack's CPU usage (no other audio app running) using the Edirol against a USB M-Audio Transit. I noticed on both computer the CPU usage to be much higher with the firewire interface than with the USB. On my laptop goes up to 15% or more and 8% on my desktop (Centrino Duo @ 1.7GHz and Core 2 Duo @ 2.1 GHz respectively) while using the USB interface the usage remains below 1%. Is this a normal behaviour of firewire interfaces? Is this a Jack related issue? Is there a recent and more efficient version of Freebob (ffado maybe?) than the one from the Ubuntu repos? Cheers, Hector