Bug 431847

Summary:	Slow Rendering of PDFs (comparing to other rendering engines).
Product:	[Applications] okular	Reporter:	Jack <jack6566>
Component:	PDF backend	Assignee:	Okular developers <okular-devel>
Status:	RESOLVED UPSTREAM
Severity:	normal	CC:	aacid, oliver.sander
Priority:	NOR
Version First Reported In:	20.12.1
Target Milestone:	---
Platform:	Arch Linux
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Jack 2021-01-20 12:20:17 UTC

SUMMARY
Okular renders very slowly comparing to the other rendering engines.

STEPS TO REPRODUCE:
1. Load any avarage PDF (30-40 pages, lots of text, some small-ish photos)
2. Scroll intensively
3. Compare the speed to muPDF-gl version
The difference between Okular (slow) and muPDF-GL (instantenous) is quite huge.


EXPECTED RESULT
Fix for instantenous render like the competition.

SOFTWARE/OS VERSIONS

Linux/KDE Plasma: Arch
(available in About System)
KDE Plasma Version: 5.20.5
KDE Frameworks Version: 5.78.0
Qt Version: 5.12.2

Comment 1 Albert Astals Cid 2021-01-20 21:01:27 UTC

Okular doesn't do any rendering. The rendering happens at the poppler level.

Comment 2 Oliver Sander 2021-01-21 06:04:57 UTC

In any case, this report is too unspecific.  I am not saying that what you say is wrong, but a report that can be acted upon must be more specific.  For example: "poppler renders this particular page from this particular document much slower than mupdf".