I have a server and slave setup with syncrepl, openldap 2.3.34

Here is my syncrepl stanza on the slave:

syncrepl rid=1 provider=ldap://ldap1.sample.edu.au:389 starttls=yes type=refreshAndPersist interval=00:00:01:00 retry=1,2,3,4,5,+ searchbase="dc=sample,dc=edu,dc=au" filter="(objectClass=*)" scope=sub attrs="*" schemachecking=off updatedn "cn=Replica,dc=sample,dc=edu,dc=au" bindmethod=simple binddn="cn=SyncUser,dc=sample,dc=edu,dc=au" credentials="secret"

If I do only a few updates, the sync seems quite fast.

If I run a script to make about 60,000 modifications on the master, this takes about 20 minutes to run. The slave starts updating immediately, however it soon falls behind. It takes over an hour, since the last change to the master, for the slave to be in sync.

Is this expected behaviour?