Lag when displaying laptop on monitor?!

I recently got a lenovo y40-80 and got rid of my old pc. Everything works fine on the laptop using the laptop screen and is great for travel, but when i'm home I would like to hook it up to my 24'' BenQ monitor, which has a 1ms response time. But when I connect my laptop to the monitor via HDMI, I get a huge frame-rate drop to the point where I can't even watch videos because of the delay between sound and video. I need a bigger screen when editing videos so I need to solve this issue.

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