I switched a high traffic Flask web app to PyPy a couple of years ago and we saw substantially faster response times across the board, and much higher task thro

I switched a high traffic Flask web app to PyPy a couple of years ago and we saw substantially faster response times across the board, and much higher task throughput from our background worker machines, many of which were pegged 24/7. We had so much less baseline load afterwards that we were able to scale down a bunch of instances. The transition only took a few hours of effort fixing one or two incompatible dependencies, so it paid for itself in savings quickly, especially vs an approach of trying to rewrite the slowest bits in a faster language.