Anthropic made claude.ai 3x faster in two weeks with Claude self-optimizing performance

Anthropic ran a two-week sprint in August that made four core journeys on claude.ai and the desktop app about 3x faster. Cold-load time to a typeable page dropped from 3.1s to 0.55s, starting a new Claude Code session from 0.8s to 0.3s, and loading a Claude Cowork cloud session from 2.6s to 0.73s. The team ran everything from a single Slack channel where Claude Tag (beta, running a research model close to Opus 5.5) analyzed Datadog data, built benchmarks, proposed and shipped improvements, and watched every deploy — humans set goals, made tradeoffs, and approved changes. Over 3,000 changes were merged with zero customer-facing incidents or rollbacks. Optimizations included baking a static composer into HTML, precompiling a V8 code cache, keeping the composer mounted across conversations, prefetching sessions on hover, and cutting sidebar re-renders by 90%. The team also built deterministic lab benchmarks (Valgrind instruction counts, React commit counts, V8 call counts) so Claude could validate optimizations without waiting for production deploys.

The Claude team made claude.ai 3× faster in two weeks and published their method. They used Claude itself to measure latency, find bottlenecks, and suggest fixes—prompts included. The post links to a blog; before/after metrics aren't in the snippet.