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I am using a UIDocumentInteractionController to preview small PDF files (approx 83K) using presentPreviewAnimated:.  My delegate implements documentInteractionControllerViewControllerForPreview: and returns the view controller currently at the top of the nav stack, so that the interactionController is displayed modally.

I noticed on iOS 10 when calling presentPreviewAnimated that the preview takes a very long time to load the document (5+ seconds).  While loading, a blank white screen is displayed.  Then, when clicking "Done", there is another pause of ~5s where the app becomes completely unresponsive (can't scroll or tap done again), followed by the dismissal of the preview and return to normal operation.

Steps to Reproduce:
1.  Use the UIDocumentInteractionController to preview a PDF file.
2.  Once the preview view appears, click "Done"

Expected Results:
The PDF preview renders and dismisses in a timely fashion.  Interaction is smooth and never results in a period of unresponsiveness.

Actual Results:
When the preview view appears, the preview pane is blank (white) for 5+seconds before the PDF is rendered in the view.

When clicking done, the UI freezes for another 5-10 seconds before the preview is dismissed and the app returns to normal operation.

Version:
iOS 10.0.2