| # Web Performance Objectives |
| |
| [TOC] |
| |
| ## 2021 Q2 Objectives |
| |
| * Publish public proposal on **smoothness**. |
| * **Responsiveness**: |
| * Socialize publicly our definition of interactions and normalization options. |
| * Implement [interactionID](https://docs.google.com/presentation/d/1nxNFwsGqYy7WmIZ3uv_0HsSIQMSXQA9_PqlOD3V74Us/edit#slide=id.p). |
| * Enable exposing information about **Single Page Apps** via |
| [navigation IDs](https://docs.google.com/presentation/d/1snPIu2GJ_JO7esJ_3YmOAiXC_g4PeQW3jclYx1u3Qzs/edit#slide=id.p). |
| * Expose performance information about **back-forward cache** navigations to performance timeline. |
| * Specify and launch redefined (window-based) **Cumulative Layout Shift**. |
| * Ship **JS Sampling Profiler**. |
| * Facilitate **Resource Timing** integration into Fetch and change implementation as needed. |
| * Obtain more accurate **abandonment** rates on Chrome to determine what to do about the problem. |
| * Implement and ship [droppedEntriesCount](https://w3c.github.io/performance-timeline/#dom-performanceobservercallbackoptions-droppedentriescount). |
| |
| ## 2021 Q1 Progress |
| |
| * **performance.measureMemory** was shipped! See the blog [post](https://web.dev/monitor-total-page-memory-usage/). |
| * **Single Page Apps**: |
| * Provided feedback to the AppHistory [explainer](https://github.com/WICG/app-history/blob/main/README.md). |
| * Discussed how to extend performance timeline to include SPAs in the WebPerf WG. |
| * Improved **abandonment** data on Chrome to account for FCP more accurately. |
| * Continued work on **smoothness** and **responsiveness** proposals. |
| * Proposed way to include **back-forward cache** performance information to the WebPerf WG. |
| * Organized **A/B testing workshop** to better understand the problem space: see |
| [notes](https://docs.google.com/document/d/1rmVjH7-5hGk_VB0EwErM1tcEVz100XZDYlaSd75WbRE/edit?ts=601c4a9c). |
| * Completed GC integration work for the **JS Sampling Profiler**. |
| * Various improvements for **Layout Instability** which especially impact carousels. See |
| [changelog](https://chromium.googlesource.com/chromium/src/+/main/docs/speed/metrics_changelog/cls.md). |
| * Decided redefinition of **Cumulative Layout Shift** and announced in [post](https://web.dev/evolving-cls/). |
| |
| ## 2021 Q1 Objectives |
| |
| * **performance.measureMemory**: ship the API. |
| * **Single Page Apps**: |
| * Publish an explainer about SPA issues. |
| * Determine whether User Timing hints conventions are still useful. |
| * **Abandonment**: |
| * Gather concrete feedback form analytics providers and other potential users of this API. |
| * Improve confidence on the abandonment rates computed by implementing a renderer-side flushing. |
| * Update analysis on rates when the above fix has reached Chrome Stable. |
| * **Smoothness**: |
| * Continue refining the definition of dropped frames. |
| * Move proposal to WICG. |
| * **Back-forward cache**: |
| * Expand scope to include FCP and FID in the values reported after back-forward navigations. |
| * Investigate backwards compatibility of adding new entries and propose an API shaped based on the outcome. |
| * **Responsiveness**: |
| * Investigate correctness of existing internal metrics and implement fixes as needed. |
| * Further investigate scrolling performance and how it should be integrated with metric. |
| * Define user interactions that we care about for this API. |
| * Create a manual test corpus to test ideas about the 'end time' of a user interaction. |
| * **First Contentful Paint**: improve implementation to pass more |
| [tests](https://wpt.fyi/results/paint-timing?label=master&label=experimental). |
| * **Longtasks**: add system time, including garbage collection |
| ([bug](https://bugs.chromium.org/p/chromium/issues/detail?id=1091754)). |
| * Present proposal to security team, and begin socializing the proposal externally. |
| * **A/B testing**: organize workshop on client-side A/B testing. |
| * **JS Sampling Profiler**: |
| * Complete the GC integration work. |
| * Ship the API. |
| |
| ## 2020 Q4 Progress |
| |
| ### New web performance APIs |
| |
| * **performance.measureMemory**: added support for cross-origin iframes in the same process and sent |
| [Intent to Ship](https://groups.google.com/a/chromium.org/g/blink-dev/c/RExJ9a3SmQw). |
| * **Page abandonment**: made some data available publicly and socialized it in a |
| [blogpost](https://calendar.perfplanet.com/2020/abandonment/). |
| * **JS Sampling Profiler**: |
| * Implemented the API so it requires COOP/COEP and gated it behind Document Policy. |
| * Finished a prototype of GC integration for the V8 sampling profiler (which will help reduce profiler startup time). |
| * Landed some initial support for code object refcounting. |
| * **Smoothness**: published a proposal around dropped frames and presented it at TPAC. |
| * **Back-forward cache**: determined that it is backwards compatible to expose a PerformanceNavigationTiming |
| entry for back-forward navigations. |
| * **Responsiveness**: |
| * Investigated some internal metrics, but found some metric quality issues that need to be investigated. |
| * Started brainstorm on capturing asynchronous work as well as which user interactions to capture. |
| * Did investigation on scrolling and determined that in most cases pages do not seem to suffer from poor |
| scrolling performance. |
| |
| ### Existing web performance API improvements |
| |
| * **Largest Contentful Paint**: include removed nodes ([bug](https://bugs.chromium.org/p/chromium/issues/detail?id=1045640)) |
| and ignored images occupying the full viewport ([bug](https://bugs.chromium.org/p/chromium/issues/detail?id=1133883)). |
| * **Cumulative Layout Shift**: implemented various fixes, see |
| [changelog](https://chromium.googlesource.com/chromium/src/+/main/docs/speed/metrics_changelog/README.md). |
| |
| ## 2020 Q4 Objectives |
| |
| ### New web performance APIs |
| |
| * {#measure-memory-20204}**performance.measureMemory**: |
| * Add support for cross-origin iframes. |
| * Send Intent to Ship and ship --- API would become available early next year. |
| * {#spas-20204}**Single Page Apps**: |
| * Publish document for feedback on measurement issues, attributions issues, and other issues specific |
| to SPAs. |
| * Land support for User Timing hints in Chrome, and get 2+ frameworks to start using such hints. |
| * {#page-abandonment-20204}**Page abandonment**: publish data on abandonment rates, making a case for or against |
| an abandonment API. |
| * {#js-profiler-20204}**JS Sampling Profiler**: |
| * Implement the API so it requires COOP/COEP. |
| * Add support for warm codemap initialization. |
| * Add web platform tests. |
| * _(Stretch)_ Send Intent to Ship. |
| * {#smoothness-20204}**Smoothness** (FrameTiming): |
| * Discuss and socialize API shape. |
| * Propose API on WICG. |
| * Start a TAG review. |
| * {#bf-cache-20204}**Back-forward cache**: document and socialize a concrete proposal on a web API that supports |
| monitoring performance of sites on browsers that may perform back-forward navigations. |
| * {#responsiveness-20204}**Responsiveness**: |
| * Investigate internal metrics and potentially add new metrics to capture end-to-end responsiveness. |
| * Document how popular frameworks handle user interactions. |
| * Brainstorm on how to expand Event Timing to capture user handling for asynchronous work and to handle multiple |
| events referring to a single user interaction. |
| * Complete on-going investigation on whether scroll performance is also a problem in the web that needs a web API. |
| |
| ### Existing web performance API improvements |
| |
| * {#lcp-20204}**Largest Contentful Paint**: |
| * Complete [investigation](https://bugs.chromium.org/p/chromium/issues/detail?id=1045640) on removed nodes |
| and if needed update the API. |
| * [Ignore](https://bugs.chromium.org/p/chromium/issues/detail?id=1133883) images that occupy the full viewport. |
| * {#cls-20204}**Cumulative Layout Shift**: evaluate the impact of triggering on empty or invisible content and update |
| [spec](https://github.com/WICG/layout-instability/issues/61) and implementation accordingly. |
| * {#fcp-20204}**First Contentful Paint**: improve implementation to pass more |
| [tests](https://wpt.fyi/results/paint-timing?label=master&label=experimental). |
| * {#rt-worker-20204}**Navigation Timing**: [Fix](https://crbug.com/925239) encoded/decoded body sizes when going |
| through service workers. |
| |
| ## 2020 Q3 Progress |
| |
| ### New web performance APIs |
| |
| * [performance.measureMemory](#measure-memory-20203): |
| * Spec was reviewed and polished. |
| * API support was added for workers (available from Chrome 87). |
| * [Page abandonment](#page-abandonment-20203): improved data was gathered, but more accuracy improvements are needed. |
| * [VisibilityStateEntry](#page-visibility-20203): |
| [explainer](https://docs.google.com/document/d/1l5kHiJRkdQwEN-CYI5_mUNODhQVB5rCyjN4jHDdXDHA/edit#), |
| [discussion](https://github.com/w3c/performance-timeline/issues/105), and TAG |
| [review](https://github.com/w3ctag/design-reviews/issues/534) kicked off, but no consensus yet on API shape. |
| * [FrameTiming](#frame-timing-20203): a lot of research on defining a good metric to capture smoothness. |
| * [isInputPending](#fb-driven-20203): shipped and available from Chrome 87! |
| |
| ### Existing web performance API improvements |
| |
| * [LargestContentfulPaint](#lcp-20203): |
| * Did analysis on how LCP would change when removed content is included. |
| * Ignored paints occurring with opacity 0. |
| * CumulativeLayoutShift [fixes](https://chromium.googlesource.com/chromium/src/+/main/docs/speed/metrics_changelog/cls.md): |
| * Ignored shifts from video thumb sliders. |
| * Fixed computations for ink overflow and transforms. |
| * Updated computations when child moves alongside their parent element. |
| |
| ### Interop |
| |
| * [Web vitals specs](#vitals-specs-20203): triaged new |
| [issues](https://github.com/search?q=is%3Aissue+created%3A2020-06-01..2020-09-30+repo%3Awicg%2Flayout-instability+repo%3Awicg%2Flargest-contentful-paint+repo%3Awicg%2Fevent-timing&type=issues) |
| as well as existing ones. |
| * [Paint Timing](#paint-timing-20203): fixed two FCP tests by improving our implementation. |
| |
| ## 2020 Q3 Objectives |
| |
| ### New web performance APIs |
| |
| * {#measure-memory-20203}Continue [previous work](#measure-memory-20202) on **performance.measureMemory**. |
| * Extend the scope of the API to workers and cross-site iframes. |
| * Do a review over the spec and polish it. |
| * {#spas-20203}Continue [previous work](#spas-20202) on **Single Page Apps** (SPAs). |
| * Complete partnerships with frameworks and begin gathering data using the strategy based on User Timing annotations. |
| * {#page-abandonment-20203}Continue [previous work](#page-abandonment-20202) on **page load abandonment**. |
| * Decide a path forward for a potential new web API based on data from the metric we recently implemented. |
| * {#page-visibility-20203}Continue [previous work](#page-visibility-20202) on exposing full |
| **[Page Visibility](https://github.com/w3c/page-visibility/)** history. We intend to spec and ship the |
| [VisibilityStateEntry](https://docs.google.com/document/d/1l5kHiJRkdQwEN-CYI5_mUNODhQVB5rCyjN4jHDdXDHA/edit). |
| * {#frame-timing-20203}Work on the |
| **[Frame Timing](https://docs.google.com/document/d/1t3A56iTN01ReEELJ18_jLYrvc13L3hDTXWK46AafKwE/edit)** proposal. |
| * Draft a spec. |
| * _(Stretch)_ Land a prototype of the API. |
| * {#fb-driven-20203}Continue [previous work](#fb-driven-20202) on Facebook-driven APIs. |
| * Based on the iframe layerization experiment results, send Intent to Ship for **isInputPending**. |
| * _(Stretch)_ Implement warm initialization logic for the **JS Self-Profiling** API. |
| |
| ### Existing web performance API improvements |
| |
| * {#lcp-20203}Improve quality of **[Largest Contentful Paint](https://github.com/WICG/largest-contentful-paint)**. |
| * Decide whether LCP including removals is better than the current definition (which excludes removals). |
| * Address problems with LCP not correctly accounting for opacity in some cases due to optimizations in paint code: see |
| relevant [bug](https://bugs.chromium.org/p/chromium/issues/detail?id=1092473). |
| * {#normalization-20203}Brainstorm ideas around better **normalization** techniques for existing web performance metrics and |
| socialize these ideas with the W3C Web Perf WG. |
| |
| ### Interop |
| |
| * {#vitals-specs-20203}Triage spec issues filed on GitHub. We intend to give higher priority to feeedback on |
| [web vitals](https://web.dev/vitals/) specs. |
| * {#event-timing-20203}Reduce WPT test flakiness on **[Event Timing](https://github.com/WICG/event-timing)**. |
| * {#paint-timing-20203}Change more of Chrome's **[Paint Timing](https://github.com/w3c/paint-timing)** implementation to pass more |
| of the currently failing WPTs. |
| |
| ## 2020 Q2 Progress |
| |
| * [performance.measureMemory](#measure-memory-20202): |
| * Crafted a plan to enable extending the API to workers as well as to cross-site iframes with the appropriate COEP headers. |
| * Drafted a [spec](https://ulan.github.io/misc/measure-memory-spec/), but it requires review. |
| * [Single Page Apps](#spas-20202): |
| * Designed a strategy for routing frameworks to report the start and end of SPAs via User Timing. |
| * Began conversations with such frameworks but haven't started gathering data with the strategy we designed. |
| * Presented our data-driven approach to the W3C Web Perf WG. |
| * [Page abandonment](#page-abandonment-20202): Socialized a proposal for how to define abandonment and brainstormed ways in which |
| we could expose the data to web developers. However, we have not yet reached a decision on how we plan to expose the data because |
| there is no one actively working on solving design issues with [Origin Policy](https://wicg.github.io/origin-policy/). |
| * [Event Timing](#event-timing-20202): Shipped the API, which should be available on Chrome 85 (see chromestatus |
| [entry](https://www.chromestatus.com/feature/5167290693713920)). |
| * [Page Visibility](#page-visibility-20202): Socialized our proposal and based on feedback will work on shipping |
| VisibilityStateEntry (see the [explainer](https://docs.google.com/document/d/1l5kHiJRkdQwEN-CYI5_mUNODhQVB5rCyjN4jHDdXDHA/edit)). |
| * [Layout Instability sources](#cls-sources-20202): Shipped the `sources` attribute, which should be available on Chrome 84 (see |
| chromestatus [entry](https://www.chromestatus.com/feature/5712483207610368)). |
| * Fixed layout shifts being reported from controls in the video element, see relevant [bug](https://crbug.com/1088311). The fix is |
| available on Chrome 85. |
| * [Largest Contentful Paint removal](#lcp-removal-20202): Added a metric that computes an experimental version of LCP which |
| includes content that is removed from the page. We're waiting to get Stable data in order to decide whether this is an |
| improvement over the existing LCP metric. |
| * [Final Largest Contentful Paint](#final-lcp-20202): Wrote a |
| [proposal](https://docs.google.com/document/d/1a24lxTmSycox5HS1mdtj09Sinf1mJCifdv-oREUJQ1A/edit) on how to surface the final LCP |
| candidate to a page, but this work has been deprioritized for the time being. |
| * [Paint Timing](#paint-timing-20202): Implemented a couple of fixes and now pass two more tests, but more work is needed to pass |
| all of them. |
| * [Documentation](#documentation-20202): Submitted feedback on some of the metrics content on web.dev, most of which was actioned |
| upon. Updated MDN entries for core web vitals metrics. |
| * [Facebook-driven APIs](#fb-driven-20202): Landed support for predicting touch and gesture events for isInputPending. |
| |
| ## 2020 Q2 Objectives |
| |
| ### New web performance APIs |
| |
| * {#measure-memory-20202}Work towards shipping |
| **[performance.measureMemory](https://github.com/WICG/performance-measure-memory)**. |
| This API intends to provide memory measurements for web pages without |
| leaking information. It will replace the non-standard performance.memory and |
| provide more accurate information, but will require the website to be |
| [cross-origin |
| isolated](https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/crossOriginIsolated). |
| Try it out with the Origin Trial |
| [here](https://web.dev/monitor-total-page-memory-usage/#using-performance.measurememory())! |
| Deliverables for this quarter: |
| * Extend the scope of the API to workers. |
| * Draft a spec. |
| |
| * {#spas-20202}Work towards web perf support for **Single Page Apps** (SPAs). SPAs have |
| long been mistreated by our web performance APIs, which mostly focus on the |
| initial page load for ‘multi-page apps’. It will be a long process to |
| resolve all measurement gaps, but we intend to start making progress on |
| better performance measurements for SPAs by using a data-driven approach. |
| Deliverables for this quarter: |
| * Implement a strategy for measuring the performance of SPA navigations in |
| RUM, based on explicit navigation annotations via User Timing. |
| * Partner with some frameworks to gather data using said strategy. |
| * Socialize an explainer with our ideas. |
| |
| * {#page-abandonment-20202}Work towards web perf support for **page abandonment**. Currently, our APIs |
| are blind to a class of users that decide to leave the website very early |
| on, before the performance measurement framework of the website is set into |
| place. This quarter, we plan to create and socialize a proposal about |
| measuring early page abandonment. |
| |
| * {#event-timing-20202}Ship the full **[Event Timing](https://github.com/WICG/event-timing)** API. |
| Currently, Chrome ships only ‘first-input’ to enable users to measure their |
| [First Input Delay](https://web.dev/fid/). We intend to ship support for |
| ‘event’ so that developers can track all slow events. Each entry will |
| include a ‘target’ attribute to know which was the EventTarget. We’ll |
| support a durationThreshold parameter in the observer to tweak the duration |
| of events being observed. Finally, we’ll also have performance.eventCounts |
| to enable computing estimated percentiles based on the data received. |
| |
| * {#page-visibility-20202}Ship a **[Page Visibility](https://github.com/w3c/page-visibility/)** |
| observer. Right now, the Page Visibility API allows registering an event |
| listener for future changes in visibility, but any visibility states prior |
| to that are missed. The solution to this is having an observer which enables |
| ‘buffered’ entries, so a full history of the visibility states of the page |
| is available. An alternative considered was having a boolean flag in the |
| PerformanceEntry stating that the page was backgrounded before the entry was |
| created, but there was overwhelming |
| [support](https://lists.w3.org/Archives/Public/public-web-perf/2020Apr/0005.html) |
| for the observer instead. |
| |
| * {#fb-driven-20202}Provide support for two Facebook-driven APIs: |
| [isInputPending](https://github.com/WICG/is-input-pending) and [JavaScript |
| Self-Profiling](https://github.com/WICG/js-self-profiling). The |
| **isInputPending** API enables developers to query whether the browser has |
| received but not yet processed certain kinds of user inputs. This way, work |
| can be scheduled on longer tasks while still enabling the task to stopped |
| when higher priority work arises. The **JS Self-Profiling** API enables |
| developers to collect JS profiles from real users, given a sampling rate and |
| capacity. It enables measuring the performance impact of specific JS |
| functions and finding hotspots in JS code. |
| |
| ### Existing web performance API improvements |
| |
| * {#cls-sources-20202}Ship the |
| [sources](https://github.com/WICG/layout-instability#Source-Attribution) |
| attribute for the |
| **[LayoutInstability](https://github.com/WICG/layout-instability)** API. The |
| Layout Instability API provides excellent information about content shifting |
| on a website. This API is already shipped in Chrome. However, it’s often hard |
| to figure out which content is shifting. This new attribute will inform |
| developers about the shifting elements and their locations within the |
| viewport. |
| |
| * {#lcp-removal-20202}**[LargestContentfulPaint](https://github.com/WICG/largest-contentful-paint)**: |
| gather data about LCP without excluding DOM nodes that were removed. The |
| Largest Contentful Paint API exposes the largest image or text that is painted |
| in the page. Currently, content removed from the website is also removed as a |
| candidate for LCP. However, this negatively affects some websites, for |
| instance those with certain types of image carousels. This quarter, we’ll |
| gather data internally to determine whether we should start including removed |
| DOM content. The API itself will not change for now. |
| |
| * {#final-lcp-20202}_(Stretch)_ Work on exposing the **‘final’ LargestContentfulPaint** candidate. |
| Currently LCP just emits a new entry whenever a new candidate is found. This |
| means that a developer has no way to know when LCP is ‘done’, which can happen |
| early on if there is some relevant user input in the page. We could consider |
| surfacing an entry to indicate that LCP computations are finished and |
| including the final LCP value, when possible. There’s also an |
| [idea](https://github.com/WICG/largest-contentful-paint/issues/43#issuecomment-608569132) |
| to include some heuristics to get a higher quality signal regarding whether |
| the LCP obtained seems ‘valid’. If we have time this quarter, we’d be happy to |
| do some exploration on this. |
| |
| * _(Stretch)_ **[ResourceTiming](https://github.com/w3c/resource-timing)**: |
| outline a plan to fix the problem of TAO (Timing-Allow-Origin) being an opt-in |
| for non-timing information such as transferSize. This may mean using a new |
| header or relying on some of the upcoming new security primitives in the web. |
| If we have time this quarter, we’d like to begin tackling this problem by |
| socializing a concrete proposal for a fix. |
| |
| ### Interop and documentation |
| |
| * {#paint-timing-20202}**[Paint Timing](https://github.com/w3c/paint-timing)**: change the Chromium |
| implementation so it passes [new web platform |
| tests](https://wpt.fyi/results/paint-timing/fcp-only?label=experimental&label=master&aligned). |
| These tests are based on the feedback from WebKit. They intend to ship First |
| Contentful Paint in the near future! |
| |
| * {#documentation-20202}Improve the **documentation** of our APIs on MDN and web.dev. We have been |
| busily shipping new web perf APIs, but some of the documentation of them has |
| lagged behind. For instance, we’ll make sure that there’s MDN pages on all of |
| the new APIs we’ve shipped, and we’ll collaborate with DevRel to ensure that |
| the documentation on web.dev is accurate. |
