SYMPTOMS
At some moment LDAP Browser experiences a considerable slowdown, so you have to wait 2-3 seconds before it adds a new node into the left-hand side tree view panel.
CAUSE
Incorrect DNS setting or complete absence of DNS.
WORKAROUND
Change your DNS settings so that the client and server hosts have both direct and reverse resolving via DNS enabled. Another possible solution could be adding required records to the hosts (lmhosts) file.