Could be an option, but we take high audio quality as a point of pride and encode in Opus 128k by default. Audio doesn't only include speech but also any sound effects, media present in-world, etc.

But that might be an interesting experiment. Right now the low cpu usage/high quality/faily high bandwidth usage category is something we're looking to have an option for.

Lyra is a speech-only codec, so it's apples and oranges to compare with Opus for general-purpose audio compression.