Paper2D plugin can import Sprite Sheet and create sprites. But you cannot use them in materials.
So for test purposes, I slightly modified Paper2D module and instead of sprites, it creates Material Parameter Collection with information to extract pictures from sprite sheet (texture atlas).
I did not see a performance gain, but it can be useful if you don’t want to bother with adjusting the size of each texture to a power of two.
**But I do not guarantee that the extraction function works perfectly with trimmed or rotated images! **Need some tests.
https://github.com/piomerti/TextureAtlasImporter (need connected UE GitHub)