Cicada principle - the technique used there is amazing, and surely will be very useful in the future.
As for the file size, I have just realized that I chose max quality in PS, that's why file size was enormous, decreased it to medium it looks good and only weights 118K.
Probably to use such big file is not the best idea, but in this case i think this is the best option (i might be very wrong, just starting ), because one file weights 118K, if i would use separate smaller squares - there should be about 6 squares, each ~23K. Works out same.
I was trying to make BG using cicada principle, but couldn't figure out how to get it work for this BG ...