Ingo, I think OSS can offer you just very high latency. You can't get realtime with it. Did you test this "8ms" latency, is that actually waht happens?
I get latencies as low as 5~10 ms with alsa and jack.
Besides, if you configure your system right with ALSA and JACK, you don't need to run PD as root. Don't run programs as root, this is not safe.