tediously slow performance of large pdf files

archnemesis · 09-18-2011, 12:10 AM

I have downloaded a large pdf file, about 85M, which initially takes a while to load, which is fine, but whenever i go to a new page the cpu shoots up to 100% and the page takes a few seconds to load. This makes viewing the file a chore since i need to skip around a lot.

I have tried a few different viewers, but they all act the same. Why do they take so long to load each page, and is there anything i can do to speed it up?

cheers

David the H. · 09-18-2011, 04:45 AM

If a pdf is that large, it either has an absolutely humongous amount of text in it, or it's composed of images of pages rather than text. I'm going to guess the latter, as each image has to be rendered before it can be displayed.

archnemesis · 09-18-2011, 07:41 AM

Yeah they are images, but surely they shouldn't take up to ten seconds to load should they? I mean the books is about 700 pages, which means each page must be only be about 1000kb.

frankbell · 09-18-2011, 07:51 PM

The processor, its speed, and the amount of RAM could hugely affect something like this.

You might run top or htop in a terminal and observe what they report about memory usage as you manipulate the document.

David the H. · 09-19-2011, 07:35 AM

The program also has to extract the images from the pdf container before it can render them, likely adding to the overhead. I've never really seen pdf as being a very efficient storage format in any case.

DavidMcCann · 09-19-2011, 11:35 AM

PDFs do vary enormously in quality, depending on how the text was scanned and what creation tool was used. I've had a document with less than a dozen pages that was incredibly slow. If you look at the scanned books in archive.org, you can also see cases where there are two versions of the same text, one 50% larger than the other.

amani · 09-19-2011, 01:39 PM

Try :

pdf2djvu or pdftops or pdf2ps and see how well the converted document performs in okular

archnemesis · 09-20-2011, 01:03 AM

wow, djvu is way better! Page changing is instant. cheers