The graphics are great, the gameplay is cool, I've played a couple of similar games.
I haven't encountered any lag yet (maybe I haven't reached the point of heavy load), but judging by the comments and the fact that a large paragraph on the game page is dedicated to this issue, it's probably a problem. And people might not like it. Migrating saves is a good solution.
This might be a strange comment, considering I haven't encountered any lag myself yet. I'm just worried about your game, because I messed up the launch of my own game due to technical bugs. I got a lot of dislikes at the start because of this (aside from the dislikes where people genuinely just didn't like the game). Now technical problems are my personal pain.
I wish you success. I like your game:)