Comment by zbentley

Or they’re on a computer that’s doing something intensive, swapping, or in low power mode. Or they have a browser extension that does stuff before scripts run. Or their cache is emptier than usual and they’re spending a long time doing an initial fetch of the latest ad tracking package your site installed. The list goes on. That’s far too noisy a signal to decide block-or-not based on. Good enough to try to sell someone faster gear, maybe, but not more than that.