long restart time of openldap

Hi,

we have ldap servers with many ldap entries (3 million and more) these are replicating with other instances (Master-Master + Read slaves). When we need to restart and ldap due to maintenance or other problems those are taking a lot of time before they serving a requests again. It looks like that in most cases it does a full refresh of the whole tree (printed to the log) but there are is also a timespan where nothing is printed to the log but the slapd process is really busy and consuming more than one core.

We are currently using 2.5.16.1 of openldap but have experienced this with older version too. Any hint about how to improve this?

Thanks, Norbert