open ksysguard to observe cpu usage and enable "always on top" feature for its window Use Dolphin to open a folder containing hundreds or thousands of jpg files (my test folders have 902 and 2140 files) use your mouse wheel to scroll the folder content and observe Dolphin cpu usage My cpu is Intel Celeron G1820 (2 cores, 2 threads), Dolphin cpu usage varies between 25% and 30% almost all the time if preview (thumbnails) feature is enabled. CPU usage varies more if preview is disabled (between 10 and 30%).
The preview function does indeed seem to be single-threaded. We should make it multi-threaded at some point.
Dolphin 19.12.1 is affected. Operating System: Arch Linux KDE Plasma Version: 5.17.90 KDE Frameworks Version: 5.66.0 Qt Version: 5.14.0
With Dolphin 24.04 beta de cpu usage varies between 10% and 15% and the scrolling is slower than normal. Operating System: Arch Linux KDE Plasma Version: 5.90.0 KDE Frameworks Version: 5.246.0 Qt Version: 6.6.1 Kernel Version: 6.6.3-arch1-1 (64-bit) Graphics Platform: Wayland Processors: 4 × Intel® Core™ i5-4670K CPU @ 3.40GHz Memory: 15,5 GiB of RAM Graphics Processor: Mesa Intel® HD Graphics 4600