Performance metrics in Zoho QEngine
In a nutshell
Zoho QEngine captures and displays page-level performance metrics and network request data throughout test execution, including page loads and in-app navigation triggered by user interactions. This enables you to assess how pages render, load, and consume network resources as part of functional test results.
Zoho QEngine captures and displays page-level performance metrics and network request data throughout test execution, including page loads and in-app navigation triggered by user interactions. This enables you to assess how pages render, load, and consume network resources as part of functional test results.
1. Overview
Modern web applications load and change dynamically, making performance issues hard to detect if monitoring is limited to initial page loads alone. To address this, Zoho QEngine captures performance metrics throughout test execution, allowing you to understand how your application behaves under real user interactions. By surfacing this performance telemetry alongside functional execution results, QEngine enables you to detect regressions early and validate performance expectations as part of regular automation.
During a test run, QEngine uses synthetic monitoring to measure how pages load, render, respond, and remain visually stable, not only when a page first loads, but also as the application updates during use. For example, performance data is captured during single-page application (SPA) route changes, AJAX-driven content updates, and dynamic UI transitions where the page changes without navigating to a new URL. This ensures performance is evaluated wherever users actually experience delays or instability.
QEngine records key web-performance metrics such as FCP (First Contentful Paint), LCP (Largest Contentful Paint), TBT (Total Blocking Time), CLS (Cumulative Layout Shift), SI (Speed Index), and Onload, which together indicate how quickly content appears, how responsive the page becomes, and how stable the layout remains during loading. In addition, QEngine captures network-level metrics, including Duration and Transfer Size, for AJAX and resource requests, helping identify slow responses or heavy resources that contribute to performance degradation.
Performance data is organized by primary URLs. A primary URL represents a distinct webpage explicitly accessed during test execution using the OpenURL task. Each primary URL serves as the top-level grouping for its associated navigation and network activity. The transfer size and duration of every navigation associated with a primary URL are captured and displayed as part of the performance results. For every test execution, all captured performance data becomes available once the run completes, regardless of whether the test is executed individually or as part of a test plan.
2. Performance metrics in test execution preview
This section explains how to view and navigate the performance data captured during a test execution.
Run a test case, either individually or as part of a test plan.
- After execution, navigate to the Performance Metrics tab to view the collected performance data.
Inside the tab, performance data is grouped by primary URLs. For each primary URL, QEngine displays a summary of performance metrics captured for that page, such as load timing, rendering progress, and visual stability.
The following performance metrics are recorded for every primary URL: FCP (First Contentful Paint) - Time taken for the browser to render the first piece of content (text, image, SVG) on the screen.
- LCP (Largest Contentful Paint) - Time taken to render the largest visible element within the viewport, indicating when the main content becomes readable.
- TBT (Total Blocking Time) - Total time during page load where long tasks block the main thread for more than 50 ms, delaying interactivity.
- CLS (Cumulative Layout Shift) - Measures unexpected layout shifts that occur during loading within the viewport. Lower values represent higher visual stability.
- SI (Speed Index) - Indicates how quickly the visible contents of a page are populated during loading. Lower values indicate faster visual rendering.
- Onload - Time taken for the page to reach the onload event, which fires after all static page resources (HTML, CSS, scripts, images) required for initial load have finished loading.
- Click the expand icon next to a primary URL to view the duration and transfer size for the page’s navigation request. In the expanded view, QEngine displays all AJAX and resource requests triggered while the page was active, along with their associated network metrics.
- Duration - Time taken for an AJAX or resource request to complete, measured from initiation to the full response download. This includes network latency, server processing time, and the time taken to transfer the payload.
- Transfer Size - Amount of data transferred over the network for a request, including headers and payload, measured in bytes.