For the record, having played with Firefox (and not willing to support seedy noxious Google), I experienced no sound lag. (The only problem was that I let the game run for the night not to lose my progress, and there was no more sound when getting back to it, which may be a Web problem?)
I am totally stuck in level Twisting Curve… I am puzzled! I managed all the other levels at my first try and very fast without any problem, but this one mesmerizes me. This might not just be me, seeing how someone else (nyxkn) also took notice of this level. I went as far as writing the elementary moves in an algebraic-inspired way to see where the loops could fit, but this did not do the trick! X)