I also complained about the inability to save my progress. I have a Mac and it wouldn't save on Safari nor would it save on FireFox. I then used Chrome and it worked fine for me.
Doesn't matter which computer I use to play, the game itself lags terribly every time or every other time I click in a solution in one of the larger puzzles.
Takes a level or two to get used to maybe because of the isometric perspective. I suggest trusting the "shadows" more than just the mere appearance of the pieces.
We've made huge strides in performance since launch but there's always room to improve. We'll keep working on it.