I came across this when trying to verify TEIIDDES-2478.
When you have a LDAP instance with big amount of entries (in the screenshot you can see that are 931 entries) in some part, it takes long to load all attributes. After clicking Next> on the page shown in screenshot (see attachment) JBDS freezes and doesn't respond for about 3 minutes. At least we should have some message that says, that TD is loading data from LDAP.