A lone wolf made 2 new islands...1 that is 25.6x25.6km and one that is 51.2x51.2km...but as planck said...12.8x12.8km is the standard size. And also, as planck said, the islands that 25.6x25.6km and 51.2x51.2km will lag veeeeeeeeeeeery much...even on veeeeeeery good machines...that is because, if u find a way to place objects, then just think about all the objects that u will have to place...Making a 51.2x51.2 island would need 4 times as many objects as a 12.8x12.8km island...
And, as planck also said, u can not get larger islands than 12.8x12.8km islands into WRPEdit...
Garcia