Hi @mgtroyas, what you're likely observing is the disk image caching. If you increase the RAM cache, in theory, there should be less and less disk access. All those images will either take up a lot of RAM, or have to be repeatedly read from disk. There's unfortunately not a lot that can be done to remedy that. Running LaunchBox from a NAS is unfortunately not a supported scenario; there's just too much bandwidth required for the images.
That said, I am aware of the performance issues with large collections, and I'm currently working on optimizing it all. I'm focusing on loading and saving with large collections, though, as that is where the biggest issues lie (saving a game, for example, takes far too long with large collections).
Per loading all the thumbnails instead of only the ones shown, and generating the thumbnails, that is by design and can be disabled if you turn off the RAM cache. That's what the RAM cache does; it loads as many images as will fit into the cache size into RAM in order to improve the scrolling speed. Turning the RAM cache off should stop this from happening at the expense of scrolling speed, and you should observe significantly less disk access in this scenario.