- speakingHandler: check subscriptions.has() BEFORE voiceActiveUser broadcast - segment.ts: add LRU metadata cache (200 entries, avoids Discord API in hotpath) - transmitter.ts: add backpressure handling with drain queue/flush (PassThrough.write() return value was ignored — potential OOM under load) - cleanup backpressure queue on transmitter stop Co-Authored-By: Claude <noreply@anthropic.com>