How to reduce lag when scrolling in Preview?
How is the PDF compressed? If it is black and white only, it may be using a compression method that leads to choppy behaviour.

I was recently dealing with a product manual that was a black and white only scan. It was compressed using JBIG2, and it stuttered enormously when scrolling, even on a top-of-the-line MacBook.

I opened the document in Adobe Acrobat, and recompressed it using ZIP, and the scrolling problem went away entirely.

If you have Acrobat Pro, the steps I took were: Open the file -> Save As -> "Optimised PDF" -> Change the "Monochrome Images" compression dropdown to "ZIP" -> Ok.

It does increase the size of the file (from 1.2 MB to 3 MB), but I can actually skim the document now.

I think it mostly boils down to the fact that JBIG2 is compute-intensive, and Most PDF applications don't render the document much ahead of the current page.



If you don't have Acrobat, and you can post the PDF, I can take a look at it for you.