I bought yesterday lenovo y 50-70.. When my laptop not connected to charger some heavy games are not playing well.. Some pause Are comes..But it only occurs when charging is off..
well this is normal, since you are on battery the cpu and gpu are throttled to get the maximum battery life, so when you game just plug in to enjoy maximum gaming experience
if for some reason you wanna play on battery then you can by tweaking the power profile, but still i recommend playing on with charger plugged in