# Performance

- [Anthropic's Silent 'Effort' Default: A Reasonable Decision, a Transparency Failure](https://sdd.sh/2026/04/anthropics-silent-effort-default-a-reasonable-decision-a-transparency-failure.md): On March 3, Anthropic quietly changed Claude Opus 4.6's default effort level to 'medium' without telling users. An AMD executive's analysis of 6,852 sessions showed a 73% drop in visible thinking depth. Fortune, VentureBeat, and The Register covered the fallout. Here is what actually changed, why Anthropic did it, and what it means for developers who depend on Claude Code for serious work.