Too much spacings between tiles, that makes it cost alot of CPU's mem to load whole sheet
I work with this asset in Unity and don't have any problem, that's why I don't understand the problem, maybe too weak pc (I'm not suggesting just asking).
I can't see the original comment but I have noticed that many of these sheets are not power-of-2 sizes and contain duplicate flips, lots of space, etc that make these textures load very poorly on mobile.
HOWEVER, they are FREE and only take 20 minutes or so to pack into neat little 512x512 boxes that load just brilliantly on even the crummiest of devices. It's really not a problem. Anyone with serious concerns can just repack them. The tiles are GORGEOUS and I look forward to using them. You are a talented artist.