simmer - To heat a liquid, usually a stew or soup, just below the boiling point, allowing it to cook slowly; or to stay in a slow, controlled state of progress or tension, often before a larger event or change occurs.

He was simmering with anger, but he kept it inside and didn't say out loud what he was thinking and feeling.
shortcut - A simplified way to complete a task, often by bypassing steps in a process; or a path or way that reduces the usual time or distance required to reach a destination.

He surprised the teacher by figuring out a shortcut method of solving the math problem that saved time compared to the method she had taught before.