Basically, when people migrate over from Lotus Notus, their free/busy data has extra information that can cause delays or other problems when Lotus Notes tries to look up their free/busy information.
There is now an updated Lotus Notes migration program available to strip this extra information while migrating, and instructions how to remove the extra information on accounts that have already migrated.
Users who do not use Microsoft Exchange Server query free/busy data for users who were migrated to Microsoft Exchange Server 2007. When they do this, they experience delayed responses.
For example, Lotus Notes users query the free/busy data of users who previously used Notes but who have been migrated to Exchange Server 2007. When this occurs, the Notes users experience delayed responses.
This problem occurs when the Exchange Migration Wizard does not remove the additional properties in the free/busy data of a migrated user at the time of the migration.