Ink demo with nacl is here https://ink.googleplex.com/nacl/nacl.html.

It will drop stroke when FPS is low. To reproduce, inject following js to the webpage and draw with a stylus.
function OnFrame() {
	var start = Date.now();
	while(Date.now() - start < 200) {
		;
	}
	window.requestAnimationFrame(OnFrame);
}
window.requestAnimationFrame(OnFrame);