HDMI video laggy/choppy and overheating

hey guys, so i have a Sony vaio z1 (vpc-z122gx) and have been experiencing some issues lately that I've never had before. Whenever I want to play movies on my tv via HDMI, i have to go to speed mode. As i do this, it causes my laptop to shut down after a few minutes, presumably due to overheating as it gets very hot and the fans start getting very loud. Also, before this even happens the video on the screen is extremely choppy. It is impossible to even watch a movie anymore. For reference, I am not streaming these movies, they are files on my computer. I can easily watch videos on the laptops screen though without a single problem

Very frustrated, please if anyone can help it'd be much appreciated. I expect more from this laptop. I've had it for a few years now and its performed phenomenally up until this point.