The original test isn't really valid for comparing loops and your tests prove it. The for loop on my machine does 248MM ops/sec and the while (with no mutation)

The original test isn't really valid for comparing loops and your tests prove it. The for loop on my machine does 248MM ops/sec and the while (with no mutation) does 243MM, but the while loop with mutation is 0.44 ops/sec. So performance is basically the same when the workload of the loop is the same.