Problem/Motivation
comment_entity_storage_load() attempts to optimize away a database query each time entities are loaded that don't have comment fields attached.
Unfortunately when caches are cold - such as after submitting the modules page, the field check takes 125ms and 4mb of memory.
Proposed resolution
Query statistics just-in-time and in bulk to avoid needing the loading etc and the field checks.
Remaining tasks
Uploading a patch for #1, but I think we should do #2 (which will be slightly more work).
User interface changes
API changes
New service
New data-types