Evaluate how the widgets on a page perform against performance benchmarks that you specify.

By default, the performance analyzer is enabled for the service portal.

Here are some benchmarks to analyze the performance.

You can Open Performance Analyzer as shown above.

Then you can click on validate.

You can get the results below like:

More Information — https://www.servicenow.com/docs/bundle/yokohama-platform-user-interface/page/build/service-portal/task/analyze-page-performance.html