Easy GIF Animator is designed to work with images that do not exceed 1000 x 700 pixels. Each separate frame image should be no more than 20 kb and it is recommended that the total size of the animated GIF file does not exceed 1000 kb. So generally it is recommended that your images do not exceed the size of regular web banners and pictures.
Animated GIF file format as such was not designed for large, full-screen images. It was designed for web banners and animated web pictures of small or medium size only. This means the Easy GIF Animator can not handle huge full-screen GIFs, because the GIF file format was not designed to cope with this amount of data.