If your heater was broken all winter you probably had no need to start a fire in the fireplace if you had an HTC One M9 in your pocket. It suffered from overheating early on. Eventually HTC implemented throttling when the phone got too hot. It's great that you no longer have to worry about your phone melting in your pants, but not at the expense of performance!
The Enhanced Thermal Configuration Mod for the HTC One M9 allows you to unleash the Snapdragon in your M9 without having to worry about destroying your phone with overheating. Applying the mod is pretty simple just grab a specific file from the link below and add it to the correct directory. Then reboot your phone and you'll be good to go. Head to the thread below for the download and full instructions.
via XDA