Hello! The stuttering issues are finally over! I took my laptop apart again and really took apart the fans as well and there was a big layer of dust on them. After removing it and playing FFXIV with the cooling pad, the game stays at around 60/70 degrees! I also had no more stuttering issues since then so it seems the cause was the heat after all!

Thank you very much for helping me with this and checking everything with me. I am very grateful! Thank you!