Having many such processes is not uncommon and not considered an issue per se.
If you are looking into optimising general Qlik Sense Enterprise on Windows performance, please see Optimizing Performance for Qlik Sense Enterprise.
Environment:
Qlik Sense Enterprise on Windows
PostgreSQL uses a multi-process architecture. In an empty system you will see anything from two to five processes. Once clients start to connect, the number of processes will increase.
The idea behind this is to prevent one crashing thread from being able to take the entire application with it.