Metrics

Metrics

The following metrics are measured. The tool is modular and more custom metrics can be added.

Firefox

Metrics in firefox are calculated using requestAnimationFrame and mozAfterPaint

• dom_content_loaded_time
• dropped_percent
• load_time
• mean_frame_time
• first_paint

Internet Explorer

Metrics are calculated using requestAnimationFrame and window.navigation.timing.msFirstPaint

• dom_content_loaded_time
• dropped_percent
• load_time
• mean_frame_time
• first_paint

TODO: Use xPerf for calculating GPU timings

Chrome

Code ported from Chromium Telemetry Smoothness and Loading benchmarks. Data is collected from timeline (developer tools) events and about:tracing BenchmarkInstrumentation::ImplThreadRenderingStats and BenchmarkInstrumentation::MainThreadRenderingStats. Most sites use the metrics in bold for comparisons.

• average_commit_time
• average_num_layers_drawn
• average_num_missing_tiles
• CompositeLayers
• DecodeImage
• dom_content_loaded_time_ms
• dropped_percent
• EvaluateScript
• EventDispatch
• FireAnimationFrame
• first_paint
• FunctionCall
• GCEvent
• jank
• Layout
• load_time_ms
• mean_frame_time
• mostly_smooth
• Paint
• PaintSetup
• ParseHTML
• percent_impl_scrolled
• Program
• RecalculateStyles
• ResizeImage
• texture_upload_count
• TimerFire
• total_texture_upload_time