GoKawiilAnthropic's Claude Code message threads cut response lag, not token cost
Anthropic has enabled 'message threads' by default for most Claude Code users, a feature that sends only changed data since the last turn instead of re-uploading the entire conversation history with each request. Anthropic reports this cuts time-to-first-token by a median of 35%, though total token usage and cost remain unchanged. API users can enable the feature manually via a 'thread' parameter.