The free public /audit endpoint allows 5 audits per hour per IP address. The limit exists to keep cost-to-serve low so the free tier can stay free.
If you hit the limit you get a 429 response with a styled card showing the time until reset and a sign-up CTA. Solo and Pro tiers schedule audits in the background and don't share the public-IP rate-limit pool.
Every audit is processed end-to-end (HTTP fetches + 10 category scorers); typical run time is 200-2000ms depending on how many resources your site responds with.