Version: (using KDE 4.2.0) Installed from: Mandriva RPMs Okular feels much more responsive when the thumbnails used in the sidebar have already been created. I think it would make sense to have the thumbnails pre-rendered in aggressive mode.
Thumbnails are not preloaded in greedy mode either.
I can confirm that not all thumbnails are preloaded in, for example, a 15 page PDF (with greedy settings). Okular Version: 1.7.3 KDE Frameworks Version: 5.60.0 Qt Version: 5.12.4