A site can pass every check and still be too slow to use. A slow alert tells you when response times stay above a limit you set. It is separate from outages: no incident opens, and slow time doesn’t count as downtime.
Set a limit
- Create or edit a Website or API, Port or Ping monitor.
- Enter Alert when slower than (ms), such as 2000. Anything from 50 to 60,000 works; leave it empty to turn slow alerts off.
- Save the monitor.
How it works
- After each successful check, the last three successful checks are compared with the limit. When all three are slower, the monitor turns slow (amber) and its channels get a slow alert with the average time.
- When the last two are at or under the limit again, the channels hear that it is fast again.
- Failed checks and the re-checks of failures don’t count.
- Slow alerts go out right away, without escalation delays, to every channel of the monitor except SMS. Webhooks get the events
monitor.slowandmonitor.fast. - Status pages that show the monitor mark it Degraded while it is slow.
What is timed
For websites and APIs, the whole request: redirects, DNS, connecting, TLS, the wait for the server and the download. For ports, opening the connection; for ping, the round trip. On the monitor’s page, the response time chart shows the median and p95, and each check is split into DNS, connect, TLS, server and download, so you can see where the time goes.
Choosing a limit
Set it well above the usual, for example twice the p95 of the last week, so one busy minute doesn’t alert. Since three checks in a row must be slow, the interval decides how soon you hear: with 1-minute checks, after about three minutes.
Page speed alerts
Response time is how fast the server answers. How fast the page feels in a browser is measured by a site health monitor: once a day, Google Lighthouse loads the start page and up to 4 more, on mobile and desktop. Under Alert on a slower page, choose a mobile score of 90, 75, 50 or 30. The alert goes out once when a page’s mobile score falls below it, not every day it stays there.
More on page speed monitoring, and read about website response time.