Maxed out my loop speed with the "double uncollected coins" skill right before the "collect uncollected coins" skill. Since the coins aren't considered collected until they reach the king's tower, they kept duplicating midair, creating a mass of midair coins that duplicated faster than they were collected, and slowing the game to about one frame every five or ten seconds, said frames being punctuated by the coin collection sound. My laptop started softly whirring. Firefox gave me around twelve notifications to close the tab to improve browser speed. In the time I wrote this review, one in-game second passed.
10/10, couldn't ask for a more fun experience.