Huh, interesting. I haven't gotten to this point yet but was kind of wondering about this. Does this mean that Google does not use any sort of indexing, or is it not that great? I haven't seen any documentation about the internals of Gmail so I can only wonder.

I know with Dovecot without proper (and properly stored... not on NFS) index files, after about 9-10gigs of storage, IMAP and IMAP related tasks became super slowwwww.