For the information schema.processlist:
Why are there no indexes on any of the fields (for example, a
pk on ID)? Is this something that is not written through 'via sql' and is only reading directly from the storage layer to show the stats, or why isn't this table (and all other
information_schema tables) constructed like a normal relational table?
And from the top of the mysql docs about them:
The INFORMATION_SCHEMA database contains several read-only tables. They are actually views, not base tables, so there are no files associated with them, and you cannot set triggers on them. Also, there is no database directory with that name