I noticed a few issues with testing/awsy/perfdocs/index.rst while looking at the patch in bug 1706631, but they aren't related to the actual changes in that patch so I figured I'd file a new bug for them.
The about:memory MDN page has been migrated to source docs (at docs/performance/memory/about_colon_memory.md) so the two references should be changed to refer to that instead of MDN.
There's a short page about AWSY at docs/performance/memory/awsy.md, which is referred to by docs/performance/index.md. The content from the former should get merged into this page, and then the latter reference should be updated. The information is mostly of a historical nature, which might not be worth saving, but there's a high level overview of AWSY which is decent.
There are a few places in the "Possible regression causes" section under "Base Content Explicit" that need proper capitalization and punctuation, like "lazily load any new modules you rely on".