https://bugs.openldap.org/show_bug.cgi?id=10274
--- Comment #1 from Ondřej Kuzník ondra@mistotebe.net --- I would question the design of your experiment: it appears you have 4 write-accepting nodes and attempt to saturate each with as much write load as they will handle (global write traffic being at least 4 times of what the slowest node can handle).
When you stop the test after time t, you expect the environment to replicate (considerably) earlier than start+4*t. This is not the expected outcome, we expressly document that MPR is not a way to achieve write scaling.