She's at her best when 'the heat is on'. [=when she feels a lot of pressure; when she needs to finish something quickly]
She said things in 'the heat of the moment' [=when she was angry for a short period of time] that she later regretted.
The company has 'turned up the heat on' [=has put extra pressure on] its employees to finish the job quickly.
(..) Okay, go back by the bus and wait for me, all right? Just go back and wait. Prepare a convoy. We must secure the bomb until it detonates. Don't kill him. I want him to feel the heat. Feel the fire of million souls you failed. Goodbye, my friend. Goodbye. Keep movin' forward! (..)2012 The Dark Knight Rises