From claude.dev Blog · Raymond Wang · · 3m
How Claude.ai became 3x faster in two weeks
Claude.ai and desktop app sped up 3x in two weeks using a performance loop with AI.
In brief
Claude.ai and desktop app sped up 3x in two weeks using a performance loop with AI. Claude.ai and desktop app improved speed by 3x in two weeks through an AI-driven performance loop with automated testing and incremental rollouts. Originally reported by claude.dev Blog.
We made Claude.ai 3x faster
We improved Claude.ai and desktop app speed by 3x in two weeks using a performance loop with AI.
User feedback drove the sprint
Users reported slow performance, so we ran a two-week sprint to fix the core user experience.
We measured the key journeys
We focused on four user journeys that accounted for 95% of activity, measuring time to a typeable page, starting a conversation, loading sessions, and sending messages.
Claude found bottlenecks
Claude identified four high-impact user journeys and built benchmarks to measure performance improvements.
We set performance targets
We targeted reducing time to a typeable page from 3.1 seconds to 0.55 seconds, starting a conversation from 0.8 to 0.3 seconds, and loading sessions from 2.6 to 0.73 seconds.
Claude built the performance loop
We created a Slack channel where Claude could monitor performance, identify issues, and ship fixes without customer-facing incidents.
Claude measured performance in the lab
Claude used instruction counts, V8 call counts, React commits, style recalculations, and DOM mutations to measure performance improvements.
We cut instruction counts by 48%
Claude reduced instruction counts on the conversation message tree path by 48% and wall-clock time by 78%.
We fixed layout jank
Claude identified a layout shift issue causing 31% of web page loads to move after the page was usable without user interaction.
We improved the static composer
We baked a static composer into HTML so users could type during React initialization and precompiled a V8 code cache for faster desktop shell.
We cut sidebar re-renders by 90%
We reduced sidebar re-renders by 90% by keeping the composer mounted between conversations and prefetching sessions.
Claude found hidden issues
Claude discovered 6,900 React hooks and 900 store subscriptions in the composer’s typing path, re-rendering on every keystroke.
We fixed em dash issues
Claude fixed em dash problems by copying code blocks into one-byte strings before highlighting to avoid UTF-16 issues.
We improved streaming performance
We reduced long reply blocking from 750 to 200 milliseconds, ran on a third of the CPU, and held 120fps on a 120Hz MacBook.
We added guardrails
We built guardrails to ensure the static composer never drifted by a pixel, including tests across 14 viewport sizes and keystroke validation.
We handled edge cases
Claude traced a Chrome edge case where new-tab pages had a 10px layout shift due to Chrome resizing the page.
The one thing
Claude.ai and desktop app improved speed by 3x in two weeks through an AI-driven performance loop with automated testing and incremental rollouts.
