Power saving mode is not causing your CPU to get hot, the game or demanding application you have running is causing the cpu to overheat.
Now what is saying the tablet is overheating? Did a system message come up that you had to close and comes up no matter what app you are in, or is this something that pops up while only in a certain app. If the tablet does not feel hot to the touch, then it was just an ad for the suckers who will believe it and buy "Super-Ultra-Awesome-Device-Cleaner-Pro" or whatever they called their scam program.