Avg. Page Load Time (sec) is a Metric in Google Analytics under the Site Speed section
Avg. Page Load Time (sec) Definition: The average time (in seconds) pages from the sample set take to load, from initiation of the pageview (e.g., a click on a page link) to load completion in the browser.
How its calculated: (ga:pageLoadTime / ga:pageLoadSample / 1000)
Data Analytics & Insights Google Analytics Metrics Avg. Page Load Time (sec)