User/Groups is very slow while connecting from LDAP

I have faced the issue of LDAP openfire Users/Group. While am i clicking Users/Group tab ,it is accessing very slow.My LDAP server and Openfire server both connected in the same LAN and i am connected LDAP with ssl(636).

My openfire version is :4.5.1
java version is : openjdk–1.8.0_222
os : ubuntu 16.04 (x86_64)

This depends a lot on how many your users and groups are.

How much are they?

Present User is 950
groups is 23