Web Performance Working Group Charter

The mission of the Web Performance Working Group, part of the Rich Web Client Activity, is to provide methods to observe and improve aspects of application performance of user agent features and APIs.

Join the Web Performance Working Group.

End date 31 May 2016
Confidentiality Proceedings are public
Initial Chairs Ilya Grigorik, Google
Todd Reifsteck, Microsoft
Initial Team Contacts
(FTE %: 30)
Philippe Le Hégaret, Xiaoqian Wu
Usual Meeting Schedule Teleconferences: Bi-weekly
Face-to-face: we will meet during the W3C's annual Technical Plenary week (if space available); an additional face-to-face meeting may be scheduled by consent of the participants
IRC channel: #webperf


Web developers are building sophisticated applications where application performance is a critical feature. Web developers need the ability to observe the performance characteristics of their applications, and they need the ability to write more efficient applications, using well-defined interoperable methods.

The Web Performance Working Group's deliverables include user agent features and APIs to observe and improve aspects of application performance. These deliverables will apply to desktop and mobile browsers and other non-browser environments where appropriate and will be consistent with Web technologies designed in other working groups including HTML, CSS, WebApps, DAP and SVG.

In addition to developing Recommendation Track documents, the Web Performance Working Group may provide review of specifications from other Working Groups.

Success Criteria

In order to advance to Proposed Recommendation, each specification is expected to have two independent implementations of each of feature defined in the specification.

Out of Scope

The following items are not in scope:


The working group will deliver incremental revisions of the following specifications:

Performance Timeline
This specification defines a unified interface to store and retrieve performance metric data.
Navigation Timing
An interoperable means for site developers to collect real-world performance information from the user agent while loading the root document of a webpage. The user agent captures the end to end latency associated with loading a webpage from a web server. This includes the time associated with fetching the document from the network to the time associated to load the document within the user agent.
Resource Timing
An interoperable means for site developers to collect real-world performance information from the user agent while loading resources as specified from the root document of a webpage. The user agent captures the end to end latency associated with loading resources from a web server. This includes the time associated with fetching the resource from the network and the time associated to load the resource within the user agent. This might include:
  • timing associated with the network;
  • timings associated with loading the resource in the document;
  • a resource may be one of the following elements: iframe, img, script, object, embed and link.
User Timing
An interoperable means for site developers to capture timing information with a developer supplied name. The user agent captures the time stamp at the point and time specified in the code executing in the user agent.
Server Timing
An interoperable means for the server to communicate performance metrics about the request-response cycle to the user agent, and a JavaScript interface to enable applications to collect, process, and act on these metrics to optimize application delivery.
Page Visibility
An interoperable means for site developers to programmatically determine the current visibility of a document and be notified of visibility changes.
Efficient Script Yielding (setImmediate)
An interoperable means for site developers to efficiently yield and receive control flow.
Timing control for script-based animations
An interoperable and efficient means for web page authors to write script-based animations where the user agent is in control of limiting the update rate of the animation.
Resource Hints
An interoperable means for site developers to give the user agent hints on prioritization of download to prerender of resources.
An interoperable API for site developers to asynchronously transfer data from the user agent to a web server, with a guarantee from the user agent that the data will be eventually sent.
Network Error Logging
An interoperable means for site developers to register to have network errors recorded by the user agent and sent to a uri.
An interoperable means for site developers to instruct the web browser to preload a resource using link tag before script is executed.
Frame Timing
Previously named Display Performance, an interoperable means for site developers to get frame rate and throughput of the display type of information.
CPU and Memory monitoring
An interoperable means for site developers to collect real-world CPU and memory performance information from the user agent.

In addition, the Working Group will:

The specifications will include privacy and security considerations.

Other Deliverables

The Group will produce a non-normative Primer document to facilitate the understanding of the interrelationships between its deliverables.

Other non-normative documents may be created such as:

  • Test suites for each specification;
  • Use cases documents to support development and exploration of performance-critical web platform features and APIs;
  • Primer or Best Practice documents to support web developers when designing applications with performance in mind;
  • Developer and user guides for its normative specifications;
  • Best practice document explaining how data is commonly gathered between the client and the server.


Current status of each deliverable, including implementation and other dependencies which may block it, is maintained on the Web Performance/Publications page.

Dependencies and Liaisons

The Web Performance Working Group should ensure proper reviews from the Web Applications, Technical Architecture Group, Web Application Security and Privacy groups at the minimum.

W3C Groups

Technical Architecture Group (TAG)
The WG may ask the Technical Architecture Group to review some of its specifications.
Web Applications Working Group
This Working Group develops APIs for client-side development and for markup vocabularies for describing and controlling client-side application behavior.
Web Application Security Working Group
This Working Group develops security and policy mechanisms to improve the security of Web Applications, and enable secure cross-site communication.
HTML Working Group
This group will maintain and produce incremental revisions to the HTML language. The Web Performance Working Group uses many concepts from the HTML5 specification.
CSS Working Group
The group develops and maintains CSS, which is relevant for specifications such page visibility or Timing control for script-based animations.
Device APIs and Policy Working Group
This group create client-side APIs that enable the development of Web Applications and Web Widgets that interact with devices services.
Privacy Interest Group
This group monitors ongoing privacy issues that affect the Web, investigates potential areas for new privacy work, and provides guidelines and advice for addressing privacy in standards development.
Protocols and Formats Working Group
The mission of the PF Working Group is to ensure W3C specifications provide support for accessibility to people with disabilities.

External Groups

ECMA Technical Committee 39 (TC39)
This is the group responsible for ECMAScript standardization, and related ECMAScript features like E4X. As the Web Performance Working Group will be developing ECMAScript APIs, it should collaborate with TC39.
Internet Engineering Task Force
The IETF is responsible for defining robust and secure protocols for Internet functionality, in particular HTTP. The Working Group should coordinate protocol-related work (e.g. profiles of hybi or HTTP) with the appropriate IETF WGs.


To be successful, the Web Performance Working Group is expected to have 5 or more active participants for its duration. The Chairs and specification Editors are expected to contribute one day per week towards the Working Group. There is no minimum requirement for other Participants.

The Web Performance Working Group will also allocate the necessary resources for building Test Suites for each specification.

The group encourages questions and comments on its public mailing lists, as described in Communication.

The group also welcomes non-Members to contribute technical submissions for consideration, with the agreement from each participant to Royalty-Free licensing of those submissions under the W3C Patent Policy.


Most Web Performance Working Group Teleconferences will focus on discussion of particular specifications, and will be conducted on an as-needed basis. Note the Decision Policy below with regards to synchronous meetings.

This group primarily conducts its work in github issues and on the public mailing list public-web-perf@w3.org (archive). The public is invited to contribute to the github repositories and post messages to the list. Regular activity summaries around the github repositories will be provided.

Information about the group (deliverables, participants, teleconferences, etc.) is available from the Web Performance Working Group home page.

The group may use a Member-confidential mailing list for administrative purposes and, at the discretion of the Chairs and members of the group, for member-only discussions in special cases when a participant requests such a discussion.

Information about the group (for example, details about deliverables, issues, actions, status, participants) will be available from the Web Performance Working Group home page.

Decision Policy

As explained in the W3C Process Document (section 3.3), this group will seek to make decisions when there is consensus and with due process. The expectation is that typically, an editor or other participant makes an initial proposal, which is then refined in discussion with members of the group and other reviewers, and consensus emerges with little formal voting being required. However, if a decision is necessary for timely progress, but consensus is not achieved after careful consideration of the range of views presented, the Chairs should put a question out for voting within the group (allowing for remote asynchronous participation -- using, for example, email and/or web-based survey techniques) and record a decision, along with any objections. The matter should then be considered resolved unless and until new information becomes available.

Any resolution taken in a face-to-face meeting or teleconference is to be considered provisional until 10 working days after the publication of the resolution in draft minutes sent to the working groups mailing list. If no objections are raised on the mailing list within that time, the resolution will be considered to have consensus as a resolution of the Working Group.

This charter is written in accordance with Section 3.4, Votes of the W3C Process Document and includes no voting procedures beyond what the Process Document requires.

Patent Policy

This Working Group operates under the W3C Patent Policy (5 February 2004 Version). To promote the widest adoption of Web standards, W3C seeks to issue Recommendations that can be implemented, according to this policy, on a Royalty-Free basis.

For more information about disclosure obligations for this group, please see the W3C Patent Policy Implementation.

About this Charter

This charter for the Web Performance Working Group has been created according to section 6.2 of the Process Document. In the event of a conflict between this document or the provisions of any charter and the W3C Process, the W3C Process shall take precedence.


Ilya Grigorik, Philippe Le Hégaret, Todd Reifsteck