I got stable results by 36% higher than presented in README.
2020/06/22 10:45:21 1000000
2020/06/22 10:45:21 Elapsed 732.9921ms
2020/06/22 10:45:21 Msg per sec 2728542 

Intel Core i7-4720HQ 2.60GHz
Total Physical Memory:     16 209 MB
Available Physical Memory: 6 399 MB