saslauthd eating all CPU [SLES 12SP4]

Hi,
we have upgraded our mailgate to SLES 12 SP4 some time ago. We are using saslauthd → imap for some services. This is working, but we see frequently very high load (4 cpu VM, load 3 to 8). It is caused by saslauthd.
A simple restart will drop the load to 0 in a few seconds. Saslauthd is working (slow) in this phase, but the
response is slow any I’d like to understand what’s going on. There are no errors or log files.
SUSE Linux Enterprise Server 12 (x86_64) VERSION = 12 PATCHLEVEL = 4 (x86_64)
rpm -qa | grep sasl
cyrus-sasl-2.1.26-8.10.1.x86_64
cyrus-sasl-plain-32bit-2.1.26-8.10.1.x86_64
cyrus-sasl-plain-2.1.26-8.10.1.x86_64
cyrus-sasl-32bit-2.1.26-8.10.1.x86_64
libsasl2-3-32bit-2.1.26-8.10.1.x86_64
cyrus-sasl-gssapi-2.1.26-8.10.1.x86_64
cyrus-sasl-saslauthd-2.1.26-8.7.1.x86_64
cyrus-sasl-gssapi-32bit-2.1.26-8.10.1.x86_64
cyrus-sasl-digestmd5-2.1.26-8.10.1.x86_64
libsasl2-3-2.1.26-8.10.1.x86_64

Any idea ?