mPulse RUM Data Loaded through September 2023, with INP + BFCache

By Nic Jansma on 01 Oct 2023

Table of Contents

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Latest mPulse RUM Data Loaded

We've completed an export of mPulse daily RUM data into the BigQuery akamai-mpulse-rumarchive project up through 2023-09-30.

This brings the RUM Archive's mPulse dataset to a running total of 394 straight days of data available since 2022-09-01. (There is also first-of-month data going back to 2021-10-01).

Interaction to Next Paint (INP) Data

From 2023-09-01 onward, Interaction to Next Paint (INP) measurements are now in the mPulse RUM data, as part of the following columns:

• INPHISTOGRAM (JSON): Histogram
• INPAVG (FLOAT64): Weighted average
• INPSUMLN (FLOAT64): Sum of the natural logarithms
• INPCOUNT (INTEGER): Number of measurements taken

At this time, INP data will not be as common as other timers such as Page Load Time (PLT*) or even First Input Delay (FID*), as capturing the INP measurement requires mPulse customers to be on a recent (1.766+) version of boomerang.

Let's review the current rate of INP data vs. something like FID:

SELECT  SUM(BEACONS) AS BEACONS,
        SUM(INPCOUNT) AS INP_BEACONS,
        `akamai-mpulse-rumarchive.rumarchive.PERCENTILE_APPROX`(
          ARRAY_AGG(INPHISTOGRAM),
          [0.50],
          100,
          true) as INP_MEDIAN,
        SUM(FIDCOUNT) AS FID_BEACONS,
        `akamai-mpulse-rumarchive.rumarchive.PERCENTILE_APPROX`(
          ARRAY_AGG(FIDHISTOGRAM),
          [0.50],
          100,
          true) as FID_MEDIAN
FROM    `akamai-mpulse-rumarchive.rumarchive.rumarchive_page_loads`
WHERE   DATE = "2023-09-30"

BEACONS	INP_BEACONS	INP_MEDIAN	FID_BEACONS	FID_MEDIAN
169,613,083	5,806,935	518	22,833,581	159

So as of 2023-09-30, out of 169.6m beacons, there were 5.8m datapoints for INP, vs. ~22.8m for FID. The INP rate should grow over time, as mPulse customers upgrade their boomerang.js versions, and as more visitors use browsers that support EventTiming/INP.

One caveat for INP data in mPulse: boomerang.js only measures INP up to the point of the first beacon, which is usually the page load event. For Single Page App (SPA) sites, INP data is also split by SPA Soft Navigations. Due to this, mPulse INP measurements may be less than CrUX INP measurements.

Back-Forward Cache (BFCache) Navigation Data

From 2023-09-01 onward, Back-Forward Cache (BFCache) Navigations are now included in the mPulse RUM data, and can be detected by looking for bfcache in the BEACONTYPE column.

BFCache data is still very small in the mPulse dataset since it requires an update to boomerang.js 1.785+.

As of 2023-09-30, we're seeing about 0.05% of beacons coming from BFCache navigations:

-- Relative popularity of each Beacon Type
SELECT  beaconType,
        SUM(BEACONS) AS BEACONCOUNT,
        (
          SUM(BEACONS) /
            (SELECT SUM(BEACONS)
             FROM `akamai-mpulse-rumarchive.rumarchive.rumarchive_page_loads`
             WHERE DATE = '2023-09-30')
        ) AS BEACONPCT
FROM    `akamai-mpulse-rumarchive.rumarchive.rumarchive_page_loads`
WHERE   DATE = '2023-09-30'
GROUP BY beaconType
ORDER BY BEACONCOUNT DESC

BEACONTYPE	BEACONCOUNT	BEACONPCT
page view	102,251,908	60.2%
spa	34,555,519	20.3%
spa hard	32,709,307	19.2%
bfcache	96,349	0.05%

This should not be interpreted that only 0.05% of navigations across the web are BFCache, as the incoming BFCache data is limited to only mPulse customers using the latest cutting-edge version of boomerang.js. I'd expect the BFCache rate to rise as adoption of the new version of boomerang.js increases.

For sites that have upgraded to the latest version of boomerang.js, and that don't have any blockers for BFCache, they are seeing a much higher rate of BFCache vs. page views. However, the mPulse dataset has data from the Top 100 sites mixed together, so we can't separate the data to only review sites that are on the latest boomerang.js.