I don't bother with sites that have cloudflare turnstyle. Web developers supposedly know the importance of page load time, but even worse than a slow loading page is waiting for cloudflare's gatekeeper before I can even see the page.
Turnstile is the in-page captcha option, which you're right, does affect page load. But they force a defer on the loading of that JS as best they can.
Also, turnstile is a Proof of Work check, and is meant to slow down & verify would-be attack vectors. Turnstile should only be used on things like Login, email change, "place order", etc.
Managed challenges actually come from the same "challenges" platform, which includes Turnstile; the only difference being that Turnstile is something that you can embed yourself on a webpage, and managed challenge is Cloudflare serving the same "challenge" on an interstitial web page.
Also, Turnstile is definitely not a simple proof of work check, and performs browser fingerprinting and checks for web APIs. You can easily check this by changing your browser's user-agent at the header level and leave it as-is at the header level; this puts Turnstile into an infinite loop.
