# 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.
- Title: How Claude.ai became 3x faster in two weeks · claude.dev Blog
- Summary: 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…
- Keywords: claude, performance, speed, desktop, react, code, streaming, fps, layout, optimization, became, faster
- Source: claude.dev Blog — https://claude.dev/blog/how-we-made-claude-ai-faster
- Author: Raymond Wang
- Published: 2026-09-23T00:00:00+00:00
- Read time: 2 min
- Topics: claude, performance, ai, speed, desktop, react, v8, code, streaming, fps, layout, optimization
## 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.
## Key takeaway

Claude.ai and desktop app improved speed by 3x in two weeks through an AI-driven performance loop with automated testing and incremental rollouts.