How Anthropic Made claude.ai 3x Faster, and the FIX Skill
The em dash that froze the page, the reload nobody could see, and a Claude skill that checks your own app for the same bugs.
On September 23, 2026 Anthropic published how it made claude.ai and the Claude desktop app about three times faster in a two-week sprint. Claude found the bottlenecks and wrote the fixes, and the team merged more than three thousand changes without a customer-facing incident or rollback. Most of what it found are ordinary web-app bugs, which is why they are worth checking for in your own code.
Anthropic's post, How we made claude.ai 3x faster in two weeks: https://claude.dev/blog/how-we-made-claude-ai-faster/
The numbers
| Measured at the 75th percentile | Before | After |
|---|---|---|
| A fresh claude.ai load, until the page is typeable | 3.1 s | 0.55 s |
| Starting a new Claude Code session | 0.8 s | 0.3 s |
| Loading a Claude Cowork cloud session | 2.6 s | 0.73 s |
These are Anthropic's measurements of its own apps. They show what the fixes did there, not what the same changes will do to a different codebase.
Keep reading
Free, for an email.
Unlocks 5 more sections, 1 copy-paste prompt, the document version, and every other guide on the site, for free. Enter your email once to keep reading.
19,000+ follow where these guides come from.No spam. Unsubscribe in one click.