Bug 513373

Summary:	Very slow to render PDF (>1 minute versus 7 seconds elsewhere)
Product:	[Applications] okular	Reporter:	Philip <philip-the-kde-user>
Component:	PDF backend	Assignee:	Okular developers <okular-devel>
Status:	REPORTED ---
Severity:	normal
Priority:	NOR
Version First Reported In:	25.12.0
Target Milestone:	---
Platform:	NixOS
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:

Description Philip 2025-12-14 18:38:55 UTC

SUMMARY


STEPS TO REPRODUCE
1. Download https://methowtrails.org/assets/wintertrails_winthroptobrownsfarm_2026.pdf (I am not attaching it to this ticket because it's larger than the bug platform upload limit)
2. Open this PDF in Okular

OBSERVED RESULT

It takes about 1 minute 3 seconds on my machine to render this PDF.
When I open the same PDF (from the local filesystem) in Firefox, it takes 7 seconds.
When I open the same PDF on my iPhone 12 Pro, it likewise takes less than 10 seconds.

EXPECTED RESULT

Okular should take about as long as Firefox does to render the PDF.

SOFTWARE/OS VERSIONS

Operating System: NixOS 26.05
KDE Plasma Version: 6.5.4
KDE Frameworks Version: 6.20.0
Qt Version: 6.10.1
Kernel Version: 6.18.0 (64-bit)
Graphics Platform: Wayland
Processors: 22 × Intel® Core™ Ultra 7 155H
Memory: 32 GiB of RAM (31.0 GiB usable)
Graphics Processor: Intel® Arc

RELATED ISSUES

Very slow render time on restaurant menu 
https://bugs.kde.org/show_bug.cgi?id=464716

The app inmediatelly crashes when trying to open a long pdf 
https://bugs.kde.org/show_bug.cgi?id=494388

PDF Rendering issues: Takes many seconds to render new page and renderings are not cleared on zooming 
https://bugs.kde.org/show_bug.cgi?id=469886