In my current project, we had the issue that the logs were flooded with CWWIM4564I warnings like the one below

[10/1/18 18:36:21:401 CEST] 00000443 LdapConnectio I com.ibm.ws.wim.adapter.ldap.LdapConnection getDirContext CWWIM4564I  The user registry is now connected to 'ldaps://activedirectory.example.com:636' LDAP Server. Or, the user registry is able to ping the LDAP server successfully.

and the ISC was very unresponsive when switching to the list of servers or the list of nodes (in an environment with 59 application servers on 13 different nodes).
Even with the workaround found by Dave Hay​, the warnings were flooding the logs (but only for the secondary Active Directory LDAP, the IBM Domino LDAP just worked).

What we did was twofold. As the context pool for the Domino based repository was already enabled, we also activated the context pool for the Active Directory repository, which cut down the number of CWWIM4564I warnings dramatically.

In addition to that, we also followed the steps Martijn de Jong outlined in his blog entry. As the transport memory size was already set to 200 and the IBM_CS_WIRE_FORMAT_VERSION was also already set to 6.1.0, we just had to add the IBM_CS_HAM_PROTOCOL_VERSION custom coregroup property with a value of 6.0.2.31.

With those two changes and a reboot, we experienced a dramatic increase in performance when using the ISC and the logs were a lot easier to read without the CWWIM4564I warnings.