I occasionally look at the leaderboard for the day, to see how long people are taking to solve the puzzles.

Top 9 of the AoC 2020 leaderboard for day 9

Some people seem to be getting through the puzzles in under 5 minutes after they go live. I can't even comprehend the puzzles in that amount of time, let alone write a solution.

What techniques do people use to get through the puzzles so quickly?

Is it possible they are cheating? I don't really think people are cheating, but their achievements are so extraordinary.