How to reduce lag when scrolling in Preview? I have a large pdf file and I was wondering how I could decrease the lag when scrolling. 

I tried breaking the file into smaller sections (roughly 20 page chunks) but that didn't help. I'm thinking scrolling is so slow because each page is some sort of image.

Are there any other steps I can take to reduce the choppiness when scrolling?
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.