The GPU PresentationFeedback parameters contain an estimated timestamp for the time when the frame will be presented on a screen. The old PresentationFeedback records the time when the CALayerTree of the frame is populated to CoreAnimation instead of the actual time when the image content of the CALayerTree is displayed on a screen. This feature improves the metrics accuracy by using the image content display time for PresentationFeedback. As a result, the time for producing a frame on a screen increases.
On average, the feature NewPresentationFeedbackTimeStamps increases the latency of INP, LCP and FCP by ~20 ms. The actual numbers can change according to the hardware screen VSync frame interval.
This feature was launched to 100% Stable on Mac on June 17, 2024 for Chrome 124 and beyond during the release period of Chrome 126. Chrome 126 was released the week of June 11.
Note: The source code change for enabling this feature was merged into the M128 branch.
