why power of 2 is better for background or tiled background ?
example ? please
From the Manual
Which you can visit with the link at the top of this page, by the way..
Power-of-two sizes
For best results, use a power-of-two sized square image for the Tiled Background (e.g. 16x16, 32x32, 64x64, 128x128...). This achieves best results in WebGL mode. The object will still work correctly with non power-of-two sized images, but the quality may be slightly reduced since the image has to be stretched to a power-of-two size before tiling. (Note this does not apply to Sprite objects, which can use any size.)