freebsd log process problem

[Bane Ivosev]

After version 2.2.32 we have an issue that occures randomly a couple 
times per day, log process gets stuck at 100% CPU usage with message

dovecot: log(56027): Warning: Log connection fd 20 listen_fd 20 prefix 
'imap: ' is sending input faster than we can write

It happens with several Dovecot version after 2.2.32 on FreeBSD 10.4 and 
11.2-RELEASE. We tried 2.2.34, 2.3.2, 2.3.4

On the same system version 2.2.32 and earlier works perfectly.

Did anyone experience similar problem?