Optimization in KDE Base
Improve the performance when creating previews for thousands of items by the following strategy:
- The previews for currently visible items are created before the previews for invisible items.
- If the user changes the visible area by using the scrollbars, all pending previews get paused.
As soon as the user stays on the same position for a short delay, the previews are resumed.
Also in this case the previews for the visible items are generated first.