A subjective impression is extremely hard to define so be careful there.
To find out what is happening with your machine, use the 'sensors' command or if you want a GUI use: "api xsensors" and call 'xsensors'.
It's actually quite nice.
My machine starts to blow and gets hotter when watching movies,
Use a similar or preferably same app to run on the different distros. My machine quickly starts venting hot air when looking at youtube videos, you could try that .... but take a note on how long it takes to start blowing.
Use 'sensors' or 'xsensors' to track CPU (and GPU) temperature and note whether the fan triggers at the about the same temp. (mine triggers at 50 deg Celsius)
Check at what speed the fan turns and how effective that is in cooling (or not).
The Helix2 had the same issue. My daughter didn't dare take the machine with her to the library due to it's noisyness.
So we found a next gen Helix (tablet) version which didn't have a fan at all.... albeit the CPU was less powerful.