[Dovecot] maildir filename with eg. ,S=1000, omitted

Hello.

I encountered the wiki entry on maildirs not long ago. In it, it is suggested that the use of ,S= and ,W= may improve performance as dovecot does not need to calculate size itself.

While my maildir filenames have ,W=, they lack ,S=.

I've grepped dovecot.conf, but I can find no option to address this.

Regards, Joseph