Claude in Chrome added Quick Mode. Instead of the standard tool-use protocol with JSON blocks, it uses a compact single-letter command language — C x y for click, T text for typing, N url for navigation. The extension sends an empty tools array to the API and parses raw text commands directly. That’s where the 3x speed improvement comes from: no JSON serialization, no structured block parsing, fewer API round-trips.

It runs on Haiku 4.5 for Pro users. Max plan users get Opus 4.6 Fast, which is even faster. The model emits commands, the extension executes them, captures a screenshot, sends it back, and loops until done.

The catch: you need to be specific about what you’re testing. “Test this page” won’t cut it. Haiku 4.5 is fast but it doesn’t reason as deeply as Sonnet or Opus — it follows instructions literally. Tell it “click the login button, enter test@example.com, submit, and verify the dashboard loads” and it nails it. Leave it vague and it wanders.

This actually lines up with what I’ve seen using Haiku in other contexts. It’s excellent at executing precise instructions, less great at figuring out intent on its own. Quick Mode amplifies that trait — the speed is real, but the quality of your prompt matters more than usual.