2d game lagging

To add to what the others have said: I generally try to keep textures for 2D games to just 1024x768 at absolute most, and the majority are 512x512 or smaller. Unity can pump thousands of smaller sprites (64x64 and down) through the pipeline at a great framerate, but you don't want to go too crazy with the larger sprite sizes, even on the PC.

Correct: I meant 1024x1024. Power of two is best.

I have the same problem. But my animations work well after 3. or 4. playing. I think Unity don't load my sprites when i instantiate my prefabs. how can i force Unity to load animation sprites before when i want to play.