I'd hope people using it wouldn't have chosen it unless they had measured performance -- doubly so if the switched to it from something else. On the other hand

I'd hope people using it wouldn't have chosen it unless they had measured performance -- doubly so if the switched to it from something else. On the other hand, common third-party benchmarks may not be useful for measuring these sorts of improvements, which take advantage of common input distribution biases. "Real world workloads" is really too much of a simplification -- people sort all shapes and sizes of data. When JS engines started getting fast(er), every engine made their own preferred benchmark because they said existing ones didn't adequately show the real-world gains their engines were providing. We shouldn't be reflexively cynical about that. If they have made good-faith measurements, it is likely that old benchmarks were "unrepresentstive" in some way. Again, "real world benchmarking" is hard, and that applies just as much to yesterday's benchmarks as today's.