The proposal generalizes the previous performance-memory proposal  that was abandoned  due to information leak of cross-origin resources. The new API addresses the information leak and process model issues raised in the previous feedback .
What is different in the new API?
- It relies on COOP+COEP  for preventing cross-origin information leaks (see "Security Considerations"). Besides security, COOP+COEP also helps implementability because the browser needs to isolate the web page from other web pages.
- It does not assume any particular process model and is defined using the standard concepts such as JS agent cluster and browsing context group.
- It has an extensible and generic interface for breaking down memory usage by type (JS, DOM, GPU) and owner. Implementers can choose the level of detail they are willing to provide based on their performance trade-offs (see "Performance Considerations").