Performance in library overview with around 500 books (Windows Version)

The library overview is currently having performance issues.

I have over 500 epub books added to FBReader since I like to have it all in overview.

But with these many books scrolling (on my 4k screen) is extreeeemely slow. Even when opening it takes around 2 seconds until all title pages are loaded.

Since for opening a single epub book FBReader is currently the fastest tool, I would like to use it.

Also it would be nice to define the size of the preview of the title page in the library. Currently I would like to have it a bit bigger for better readability. And it could be a bit filtered since it's a bit pixelated.

Ideas for performance improving:

• maybe cache the preview title image of each book
• invalidate cache on size change
• add a button to clear cache of preview title image