As a data engineer, testing with production loads is critical to performance checking, as well as finding edge cases where your assumptions about what can be expected in the data are curb stomped and send you back to the drawing board to cry and think about what you’ve done.
Same. Early on as a new dev, I failed to performance check my script (as did my qa tester) before it was released to production, and that was my first roll back ever. It was very unoptimized and incredibly slow under one of our highest density data streams. Felt like an idiot that I was good with it’s 1-2 second execution time in the dev environment.