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 don't have to see! Hi, tushy! One of you give me your underpants. I'm not wearing any. How can you not be wearing any? I'm getting heat from the guy in the hot pink thong. Look, Ross. I'll give you $ for your underpants. - Can I have the milk? - I'm almost done with it. (..)1996 TvShow: Friends Title: The One After the Superbowl: Part 1 Season: 2 Episode 12
(..) So I ran to the end of the road, and when I got there I thought maybe I'd run to the end of town. President Carter, suffering from heat exhaustion... And when I got there, I thought maybe I'd just run across Greenbow County. Now, thinking since I'd run this far, maybe I'd just run across (..)1994 Forrest Gump
(..) Where is this guy now? (African language) Don't tell me your man swindled you, I sent you six short range heat seekers and got a boat full of rusted parts. Now, you will make it right, or the next missile I send you will come very much faster. Now, minister, where were we? (African language) (..)2015 Avengers: Age of Ultron