This gets us to ~40% of one core cpu usage during playback. Good enough for a while I reckon! Paid for the internal ram usage by reclaiming some stack size headroom.
it's not clear to me that it helps *that* much, since the ogg allocs are in internal ram anyway, and the memory pressure is just a bit much
it's a pretty chonky codec, but this seems like the best way to tame its performance.