On a 8 worker nodes (16 cores, 80GB ram, 3TB SSD), we're at around 20k inserts/second, while most of the selects are running at around 100ms (besides some counts and complex queries).
If you have a lot of data and know Postgres, give it a chance.
[0] https://pexe.so
Is that 20K separate transactions or are some of the 20K inserts grouped together?
Disclaimer: don't work there, but on the Slack and the Citus team is nothing short of awesome.
https://docs.citusdata.com/en/v5.2/performance/scaling_data_...
If that has changed I'd add it to my table.
https://docs.google.com/spreadsheets/d/1sMQe9oOKhMhIVw9WmuCE...