Stability of audio (fw) driver under OSX


I currently testing different firewire audio interfaces using OSX 10.9.4. Basically all devices which come with an own firewire kext/driver, will work much more stable in Renoise. And all devices which use the Apple’s default fw driver, will start to stutter much more early… Esp. if moving around windows, resizing etc. Maybe this is a problem in later OSX versions, too?

I would like to know if there is a way

a ) from kext/driver side to make it more stable, for example, higher the priority of the apple fw driver?

b ) from Renoise side to stabilize the audio output under low latency?

Thanks for infos / ideas.