Windows will slow down app loading if not online for some time

  antivirus, c++, performance, updates, windows

a very specific problem that I can not find an old thread of.

We have a C# app developed and confused running on a Windows 10 machine updated to latest version. We are talking about a closed system that does not have an internet connection at all, except when installing everything.

Now at beginning the app loads reasonably fast. This means 0-2s for the splash screen as this is the first thing that we display. All good.

After 14 days approx. the app load time goes to 30s. This means that after initial click it takes between 20-30s for the splash screen to appear.
How to solve it? Connect the PC online for 5 minutes and again the load time is down to 0s for another 14 days… (not acceptable once the system is handed over)

Defender = have exceptions on directories and executables (no other AV in use)

Firewall = disabled

What could be the problem? Windows seems to be searching for something online. But what, it does not seem to download anything specific.

Source: Windows Questions