It's not the new .NET Core AOT feature, GP was building the DLLs and packaging the website locally.
Not GP but funny enough I ran into a similar problem with a team that also didn't know compilation and was just copy/pasting into a server.
I haven't worked with IIS in more than five years, but couldn't you change some setting to infinity so the thread never sleeps... or something like that? I remember the "5 second" thing being a problem with commercial IIS apps we deployed, and that's always how we avoided it.
The solution was just to compile the app before deploying, as grandparent did.
Even back then the general consensus was that "not compiling" was a bad idea.
Most serious developers skipped this goofiness and deployed compiled and tested builds.