Need help with gaming laptop

[mavalgreb]

Does anyone know why it do be like this. My friend bought a gaming laptop and first week he played pubg and had over 100 fps on ultra graphics but its almost 2 moths since he plays pubg and his fps now gets barely to 50 with lowest graphics. We don't understand anything about pc/laptops and have no one who knows either that's why asking reddit. Hope you can help.