shiny app slow on RSconnect but fast on IDE

hi everybody,

I have a problem on my app deployed on Rsconnect server.
While my company IT install an set up the Rsconnect server, i ran my shiny App on the ide and share it via our ethernet network by forcing the port:5050 in runApp.
that works so fine and everybody under network can access fast to my app

So, when the Rsconnect is operationnal i try to publish on them :
result :

  • on single user the app is a bite slow but correct
  • When we stress test the system and launch 10-15 user at the same time to access the app that's extremly slow (arround 45sec - 2min30) to just get the frame of the UI and frist page of the app appears slowly too...

The IT Service says that my app is probably too heavy and i have to downsize it.
So why that's ok on little desktop pc as server (no problem with the same stress test multiple user) and that's wrong with "professionnal" server?

there is a little view of my code architecture :

Dashbord on the first page (cached results) (no great calculation and visualisation here, only css kpi box : see picture)
Scheudeled .Rmd to prepare data and save as .Rds (a list that contain all my dataframe )
reactivpoll in global.R to get new .Rds every 15 minutes

How can i explain to my IT my code is ok? beacause all goes right on desktop!!! is there a particular set up for the admin rsconnect??

desktop pc spec. : dell optiplex 3050 i5 9500T 8go ram (1333mhz mono chanel)
server spec : xeon gold 6142 (4 core aviable) 32go ram redhat OS ; physically on site (big company with good network).

thanks for help.