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Sumatra PDF Reader forum

Small, fast, free PDF, EPUB, MOBI, CHM, DJVU, CBR, CBZ reader for Windows

Sumatra rendering speed is poor with huge files

Sumatra is indeed small but its rendering speed is not that impressive at all - with huge files, especially scans, it takes ages sometimes a good couple of minutes to render the entire file when it has 100mb and over..
Stefan on December 17, 2016

Helps to give a link to a sample

I am using SumatraPDF 64bit running from an USB stick on a low power celeron laptop and multipage files of about 200 MB load in well under 10 seconds with the ability to quickly jump to middle or far pages again re-rendered in a few seconds.

a 300 MB file of 842 pages can open just as fast as one with a few pages. I selected 7 files of over 100 MB at the same time and all 7 were accessible in 11 seconds total.

there are several reasons file opening can be delayed

1) if an antivirus insists it needs to check files before the app is alowed to open them.

2) they are across a network and the file needs to be locally cached for navigation.

3) the internal structure is compressed heavily and needs to be unpacked
Kieran on December 19, 2016
Is anyone have problem that if the pdf is scanned picture pdf, the memory print is very very huge after you move forward or back. It seems the Sumatra can't release memory of older render picture.
So I have to close the tab and reopen it to release memory, I have seen a scene that use about 1G memory of a scanned pdf.
Bambooin on December 20, 2016
This is an old problem. Check the following for the basic background.
D. Westoby on December 20, 2016
Thanks, Westoby. The situation what I said is when I reading scanned pdf not printing it. The program should release the memory of the previous render picture, as I seldom go back too much.

Ex. I read a scanned pdf from page 1 to page 100, the rendering memory of page 1~80 should release, as the possibility of reread them is very low. The context now maybe page 80~120.

As I explain it clearly?
Bambooin on December 21, 2016
Try version 3.0.0 (i.e., revert back to an earlier version). I'd hazard a guess that your problems will be solved.
D. Westoby on January 4, 2017
I am having the same slow rendering issue in version 3.1.2 x64 but not sure if it is because of the huge file size.

I rolled back to 3.1.1 which has better/faster rendering for me. Just as D. Westboy said, try rolling back if update doesn't work optimally for you.
Anonymous on January 8, 2017
Had a 55MB, 710 page scanned old book, the pages whereof took about 10s to open. Attempted to solve the problem by printing the PDF to another PDF with different formating. At first it broke the PDF printer, but finally I was able to generate a new file the Sumatra PDF could read correctly. (Here is the topic on the PDF24 forum about it: <>.)
bwnis_ on January 11, 2017

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