Board Thread:General Discussion/@comment-12330013-20180119182200/@comment-24577221-20180119225549

Buy an expensive decoration, such as the Tub Fountain, then sell it back. Repeat, as long as your coins hold out. If you look at the buying and selling prices, and the XP for placing the thing, this converts coins to XP, 1:1. It's not cheap, but it is fast.