Hi All,

We are running Round cube on top of dovecot and postfix as our email echo system. Main problem we are facing is that, roundcube loads really slow for big inboxes (~5000 emails). I found that, while it loads, imap process goes high in terms of CPU utilization(~90%). I asked it in some roundcube support group, They believe that it is related to dovecot not roundcube. Can you shed any light on this issue. Thanks in advance.  

Here is $dovecot -n$ output

xyz@roundcube-internal-server-1:/etc/dovecot$ dovecot -n
# 2.3.16 (7e2e900c1a): /etc/dovecot/dovecot.conf
# Pigeonhole version 0.5.16 (09c29328)
# OS: Linux 5.15.0-1024-kvm x86_64 Ubuntu 22.04.1 LTS
# Hostname: roundcube-internal-server-1
auth_mechanisms = plain login
disable_plaintext_auth = no
listen = *
lock_method = dotlock
mail_always_cache_fields = date.received
mail_cache_min_mail_count = 5000
mail_location = mbox:~/mail:INBOX=/var/mail/%u:INDEX=/var/indexes/isical.ac.in/%n