While a dedicated Hosting Server is quite lightweight in its memory usage. However, as soon as you start adding map and imagery services (especially if the map services are dedicated instances) then the memory will grow significantly and this is somewhat 'average'.
The following is a brand new server with no services on it:
The following is an established production server (during a quiet time). There are no image services, and only map services shows:
There are a good number of much larger arcsoc.exe in your screenshot, and I think that if you were to stop the larger (image) services then you may see an associated drop in your Javaw memory usage.
Generally I recommend clients to separate out the hosting server from the general purpose (map/geoproc) machine and again from the Image Server, but this is obviously dependent on a range of practical and budgetary factors. Refer to:
https://enterprise.arcgis.com/en/get-started/latest/windows/additional-server-deployment.htm#ESRI_SE...
Generally when you throw lots of different service types onto one machine, then you start to see issues like you've observed.
Scott Tansley
https://www.linkedin.com/in/scotttansley/