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.
(..) You never were that smart. Hawkins, you're up. The pilots have been shot in the head. Whoever hit it stripped the shit out of it. - Took 'em out with a heat seeker. - There's something else, Major. This is no ordinary army taxi. It looks more like a surveillance bird to me. - Pick up the trail yet? - Billy's on it. Heat seeker, Dillon. Pretty sophisticated for a bunch of half-assed mountain boys. I guess they're getting better equipped every day. There were guerrillas. They took the two men from the helicopter, (..)1987 Predator