https://core.trac.wordpress.org/ticket/54221?cversion=0&cnum_hist=56
#54221 (_transient_dirsize_cache is set to autoload=yes and kills db performance if it grows (20MB...
Blog Tool and Publishing Platform
https://dovecot.org/mailman3/archives/list/dovecot@dovecot.org/thread/BPOQOODNVFTIOD3FN44BQNYRBPPI6YMK/
Dovecot 2.4: dirsize removed - alternative for physical size quotas? - dovecot - dovecot.org
dovecotremoved