We are currently hosting a critical application behind a nginx based reverse proxy. The reverse proxy doesn't have a current WAF policy or something like that running. But we have noticed that when users start to complain about the application becoming too slow to respond to their request (I have to say that it's a huge application, in terms of futures and data volume), we see duplicates of POST in the tomcat logs, and got duplicates in Database as well. I am quitte confused on where to start the investigation and to fix the issue (the duplicates of post)? if someone could give hint !