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I have a handful of PDFs open. One of them in particular is extremely laggy, almost to the point of being unreadable. When I scroll through its pages, it's almost like an extreme version of v-sync being turned off. Very choppy.

Overall system resources are plentiful, and all of the other PDFs cruise up and down with no stuttering or problems.

I've tried closing and reopening the problem PDF to no avail. It's a small PDF, only 3MB in size, with no graphics (only programming code snippets).

Surely, it must be some type of problem with the specific PDF (I'll try opening it in another PDF-viewing program, rather than Acrobat X).

Possible corruption? Could there be some type of GPU/hardware-acceleration intervening going on? I've never heard of such with PDF-viewing.

EDIT One difference that I've noted is that the laggy file has -lots- of fonts in it, according to the PDF properties inside Adobe Acrobat. Probably 10x the amount of the other PDFs I have open.

Could this be the source of trouble? If so, is it possible to compress/strip fonts from it?

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The file could be corrupted. Try opening it up in another computer. –  Rhyuk Jul 5 '12 at 20:54
    
I'll try this. Thanks –  Coldblackice Jul 5 '12 at 21:31
    
Just get sumatra PDF, it's so much better and less laggy than adobe reader –  user322167 May 12 at 7:19

2 Answers 2

TLDR; The quality and size of the data embedded within the PDF file can have a very big impact on the speed of scrolling.

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In simplistic terms, a PDF is a container format. The content can vary widely and can be arbitrary.

Typically, the text is stored as plain text with typeface markers, and there are few images, these would be quick to scroll.

Some files have more images, which will degrade scrolling speed--worst case, the images need to be completely redrawn for every pixel of scrolling. Some PDFs are merely full-page image scans. Images are going to require more work from the computer to manipulate, since there is more data (more bytes).

Images can be at arbitrary resolutions. If I am creating a magazine ad, I would use images that were 300dpi. A 10x10 inch photo (for print) would be 3000 pixels square. Expressed in bytes, this is 3000 x 3000 x 4 bytes (minimum for CMYK color for print). That same image displayed for the screen at a particular zoom might only require the display of 300px square (for RGB = 300x300x3 bytes min), but the reader must still manipulate the original LARGE image. Depending on the reader software, an image thumbnail may be created based upon zoom factor to speed this up. If I give you a draft version PDF of that ad using acrobat's "standard" setting, it might be .5-1MB in size and be quick to display (but not very good quality if you print it out). The same ad using an "offset press" preset (without JPG compression enabled) could be be 35MB in size and you would notice a difference in speed, but the screen quality will be improved a little and the print version would be immaculate.

If the image is a vector image, depending on layers and complexity, it may need to be recalculated each time you move the page.

A lot all depends on the reader software and the manner in which the PDF was created.

AFAIK, the original PDF specification even allowed for the embedding and execution of arbitrary binary & executable files.

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It is not just images. It could also be video, or other content (including dynamically generated content via JavaScript or similar) –  soandos Jul 6 '12 at 22:31
    
'Original PDF specification even allowed for the embedding and execution of arbitrary binary & executable files'. -- This is not correct. Yes, nowadays you can embed arbitrary files. But you cannot execute them. And this was not in the original PDF spec, it was added to later version specs. Yes, you can execute: but only JavaScripts. (This makes it possible for hackers to exploit this feature -- but that was not in the spec. :-) –  Kurt Pfeifle Jul 7 '12 at 18:08
up vote 2 down vote accepted

Believe it or not, the answer to the problem was to close the other open PDFs in Adobe Acrobat. I concurrently had 5-6 separate PDFs open at once. Besides this one problematic one, all of the others flowed and scrolled through flawlessly.

After closing all of them and then just opening this one PDF, I suspect that there's a specific renderer that Acrobat isn't able to "multitask", and thus was choking on this one document.

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