Hi,
120 frames isn't a lot but how big are the textures? 120 1024x1024 textures are obviously big.... 120 32x32 not so much. Again with the atlas size, how big is the atlas size? The default is 1024, and you can go up to 4096, so that is 16x more in one texture. You haven't given me any real details so I can't really give you any more concrete advice ...