TBT 3-Hour Repro (2 hours bad, 3rd hour normal)

Warning

This page intentionally blocks the main thread with long tasks to create a very high Total Blocking Time. During the “bad hours”, the tab may become barely responsive.

Keep the tab in the foreground. If the tab is backgrounded, browsers may throttle timers and your blocking pattern may change.

Controls

“Hour” length (seconds)

Tip: set to 60 for a quick demo (1 “hour” = 60 seconds).

Bad hours

Total hours

Blocking profile

Higher profile → higher TBT growth.

Live metrics

Hour snapshots

Each time we cross an “hour boundary”, we record the cumulative TBT at that moment.

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