Not without impacting the quality of the animations. The best I can do with the least effort is change the compression format, but I have to test several settings to avoid dropping the quality of the images too much. Images are currently saved to lossless JPEG, which is way smaller than BMP and PNG, but I think they can be further compressed with lossy JPEG or WEBP, the drawback would be the considerable loss in the image quality.
Next would be removing middle frames, but that would negatively change the scenes and I wanted to preserve the original feel of Atella’s work.
Another option would be to use the original images instead of the upscaled ones, as that would reduce the size of the images by about half. Then again, this would impact the quality of the animations and they would look bad in 720p, 1080p and 1400p. (personal opinion since I played the original with all these resolutions to test)
One other thing that could be done is splitting the characters from the background and lower the weight of each frame by just having characters change, slightly reducing the size of each image, but this is monumental work for 3000+ images.