"Performance APIs, security and privacy" document

[yoavweiss]

The WG published a document on Performance APIs, security and privacy.
We should revisit this doc to see if/how it needs to be updated, and whether we're still interested in working on it.

It may also be interesting to augment it with related principles around performance and reporting. (or put those in a separate document)

[nicjansma]

@yoavweiss and I added a clause to the draft charter noting the work we're planning for 2023+ around this.

Planned items:

• Review the existing document and update it for anything new in 2023
• Add some background on principals for why measuring performance is important for the web

Updated the draft charter in ed5803c