I purchased the full game and I've had issues with extreme lag. I practically move at a snails pace. I'm not sure if it is due to my computer or the game itself. I play on windows 10.
Ah that's horrible! I'm doing little things to make the game more streamlined as far as coding goes so it might help and after the next update I'll work on one of the bigger functions in the game that could also ease things up, but if it's really as bad as you described and there is no fix in the coming updates, I can always give you a refund in that case!
Again, really sorry to hear this :(