Update, I figured out the beach ball problem: Firefox on a Mac. I switched over to Chrome, and even Safari, and it was better, so it seems like Webkit/Blink/V8

Update, I figured out the beach ball problem: Firefox on a Mac. I switched over to Chrome, and even Safari, and it was better, so it seems like Webkit/Blink/V8 is the best browser scoped runtime, for some reason.