1. Solution: Cheat a little bit. Use 30 Frames but run them half the speed. Sometimes this works.
2. Solution: This is really dirty, but sometimes I also do it: When your project is 100% finished, go to tinypng.com. Then resize all your files and pack them back in your folder. Voilá. Make sure you won't change anything in the project, since you have to do it every time you change something in c2.