What to run
Use Is This Website Down, then HTTP Headers. Both results are from Cloudflare.
How to read the result
The millisecond figure is time-to-response from Cloudflare, not full page load.
A few hundred milliseconds is normal. Multi-second times plus 200 still mean "up".
cache-control, age, and cf-cache-status on the headers page tell you whether a cache should have helped.
What to open next
Open HTTP Headers after the timing check.
Do not treat a slow 200 as down.