This is a problem with 3D rendering and Protected Mode, the solution to this is to:
1. Go to the "3D & Mutimedia" category in the list on the left.
2. Untick "Enable Hardware Rendering For Legacy Video Cards".
3. Select "Software" from the drop down menu next to Prerrered Renderer.
4. Go to the "Security Enhanced" category.
5. Untick "Enable Protected Mode at Startup".
What also helps to load the PDF more quickly:
1. Go to the "Page Display" category
2. Select "Single Page Continuous" from the drop down menu next to "Page Layout".
3. Enjoy Instant PDF loading.
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