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This behavior is caused by the connection strings which are not valid in the context of your PC. Since the connection strings are not valid on your PC, the Report Designer has to wait for the connection timeout time to pass before it can continue loading.
This behavior is logged in our system for improvement in a future version of the Reporting suite.
In the meantime you can modify the connection strings before opening the report in the Report Designer using a plain text editor. Open the report TRDX file in the text editor and modify/remove the elements under the DataSources
node in the XML:
"select * from humanresources.employee"
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