We compared PostgreSQL performance on virtual machines from 5 different cloud providers a while back, the results are on our blog at https://aiven.io/blog/postgresql-cloud-performance/ and show that there's quite a bit of variance between them.
Apples to oranges comparison. TFA is about managed service.
If you could show that RDS runs faster or slower than running PostgreSQL yourself, that would be interesting.
The post and linked slides focus on comparing different clouds, but the slides actually have a couple of comparisons of AWS Aurora, RDS and Aiven PostgreSQL performance at the end.
We'll update that with other managed services soon.