Oliver,
That does clear things up a bit, even if it is quite a bit to take in...
Previous to applying the realtime-lsm patches, audio recording/playback with multi-track hard disk recorders such as Ardour was very laggy and the audio skipped with more than 3 or so tracks. After I installed the new kernel, however, I have benchmarked it to around 20-odd tracks simultaneously playing audio and there was no skipping or patchyness.
I assumed before your explanation that the realtime-lsm patch simply enabled faster access to studio-specific audio hardware (such as my Delta 1010 PCI card/outboard).
It is apparently though different from the Preempt patches...