Bug 391972

Summary:	okular slower than evince at rendering a pdf
Product:	[Applications] okular	Reporter:	Kevin <kjslag>
Component:	PDF backend	Assignee:	Okular developers <okular-devel>
Status:	RESOLVED UPSTREAM
Severity:	normal	CC:	kjslag, simonandric5
Priority:	NOR
Version:	1.3.3
Target Milestone:	---
Platform:	Arch Linux
OS:	Linux
Latest Commit:		Version Fixed In:

Description Kevin 2018-03-17 17:59:30 UTC

Okular renders some pdfs much slower than Evince, even though both use Poppler for the pdf backend. Since the same backend is used, I would expect the pdf render time to be the same.

For example, the second page of this pdf
https://arxiv.org/pdf/1701.07837v2
takes over 3 seconds for Okular to render. However, Evince renders it almost instantly.

Or when quickly scrolling through a large pdf, Evince seems to render the pages almost instantly, while Okular renders slower than I can (quickly) scroll. Here is an example large pdf:
https://arxiv.org/pdf/1508.02595v4

I'm using Okular 1.3.3, Evince 3.26.0, and poppler 0.61.1 on Archlinux (with an Intel i7-3720QM @ 2.6GHz).

Comment 1 Christoph Feck 2018-03-30 19:12:13 UTC

The issue is in Poppler.

qpdfview is based on poppler and also needs 3 seconds to render the second page from first linked document.

Poppler has different rendering backends (splash vs. cairo) and the splash backend that is used with Okular and qpdfview is slower for this particular document.

I suggest to report it here:
https://bugs.freedesktop.org/buglist.cgi?product=poppler&component=splash backend&resolution=---

Comment 2 Kevin 2018-03-30 23:24:50 UTC

Thanks Christoph! I had no idea Poppler used two different backends. I submitted a bug here:
https://bugs.freedesktop.org/show_bug.cgi?id=105827

I suppose this is also related:
https://bugs.freedesktop.org/show_bug.cgi?id=25240