It shouldn't matter if it's a fast desktop or slow mobile (unless it's not keeping up, which is unlikely in these examples); what matters is the display rate on these devices. The demos feel very fast in a 250Hz monitor when compared to a 60Hz one.
That's right. These demos are, as they should be, using requestAnimationFrame [1]. The docs have "Warning: Be sure to always use the first argument (or some other method for getting the current time) to calculate how much the animation will progress in a frame, otherwise the animation will run faster on high refresh rate screens."
Though there are cases like iOS cross-origin frames where it's throttled to 30fps [2] for power-saving reasons.
