ACDSee old versions (2.6.1?) would preload the next image in memory while scrolling through a folder, making it extremely useful in the age of hard drives. It became bloated, but the only reasons to switch were for newer image formats, and sometimes .gifs would crash it.

FastStone Image Viewer is the performant, slick image viewer I use now.

IrfanView has some rough defaults like if you scroll to the end of a folder, a window pops up that you have to click away before you can scroll back. I use it all the time for simple editing, not viewing.