I have found, that just installed slapd (2.4.42+dfsg-2ubuntu3.2) on ubuntu 16.04 consumes 730MB+ or resident memory (RSS).
Only consumes 12 MB on my Ubuntu 16.04 system. But I don't use the build supplied by Ubuntu, I use my own. So I cannot say what Ubuntu's done to cause this.
--Quanah -- Quanah Gibson-Mount Product Architect Symas Corporation Packaged, certified, and supported LDAP solutions powered by OpenLDAP: <http://www.symas.com>