Information:

Environment

  • Synthetic Classic Portal
  • W3C metrics

 

Symptoms

According to the definitions of the W3C metrics DOM Complete Time and Total Page Load Time, we should never expect a longer DOM Complete Time than Total Page Load Time. However, I often see that in interactive charts.

Solution

DOM Complete time is the time between the navigationStart and domcomplete events. Total Page Load time is the time between navigationStart and loadEventEnd. (For more details about W3C metrics, see the W3C Metrics page in the Synthetic Classic help.)

MetricStart EventEnd Event
DOM CompletenavigationStartdomcomplete
Total Page LoadnavigationStartloadEventEnd

Since loadEventEnd is designed to be triggered after the DOM Complete event, if both events are fired and collected, the DOM Complete time for a test run cannot be longer than the Total Page Load time.

However, it could happen that real users go to the next page just after the DOM Complete event is triggered — before the page load is completed. In this scenario, only the DOM Complete time is collected, but no Total Page Load time. Because there are more data points for the DOM Complete event, this could cause the average time for DOM Complete to be longer than the average time for Total Page Load.

If you look at the averages for data points where both events are collected, the DOM Complete time should never be longer than the Total Page Load time.

If you see a longer DOM Complete time than Total Page Load time when there are data points for both events, feel free to open a Support Ticket so we can investigate the cause of this discrepancy.

Root Cause

W3C metrics are displayed in the waterfall chart when the Client (non-network) Time setting is selected for a test. You can also create a W3C Summary Report to review the W3C metric data for your tests. For details, see Waterfall Chart and Reports in the Synthetic Classic help.