It's not only you. Chrome's playback of streaming videos is a **** mess. Its HTML5 player cannot provide a proper GPU acceleration on some systems (for example, like my current laptop with Intel Iris 5100 GPU and latest Intel's drivers for it), resulting in high CPU usage (which is annoying on laptops due to noticeable increase in case warmth and fan speed), regardless of Chrome's flags/settings. Same goes for Chrome's own "PepperFlash" Flash player (which everyone should manually disable by default).
To get around this - either use different browser OR force YouTube's videos to use Flash (there are Chrome extensions which allow this). If you'll do that - don't forget to also disable Chrome's own "PepperFlash" player.
My subscription allows you people to exist on this site and makes me a better human being than you'll ever be