[Dovecot] Auth Issues - Urgent - Help!

After a few hours of running, I get tons of the following errors in my logs:

dovecot: Oct 08 07:41:50 Error: auth(default):
ldap(user@domain,x.x.x.x): Request queue is full

I removed the username and IP, obviously.

Any idea how to stop this?

I have about 5 Thousand users using horde that login ever 1-5 minutes
to refresh their page. I assume it is a setting, but I am confused as
to why it doesn't happen almost right away. It seems to take some
time to build up.

Please help! This is taking my webmail system down hourly.