[BatteryMountain]

Its not just idle, it is a bit more aggressive on cleaning up sooner after objects are de-referenced, meaning the OS gets the memory back sooner. Very useful in situation where you have many small containers/vm's running dotnet stuff, or on large applications where memory pressure is an issue and your usage pattern can benefit from memory releasing earlier.

In the old days you could tune IIS + Garbage collector manually to get similar behaviour but was usually not worth it. Time was better spent elsewhere to optimize other things in the pipe and live with the GC freezes. I suspect GC hickups should now be much smaller/shorter too, as the overall load will be lower with new GC.

[wozzio]

That aggressive release behavior is exactly what we need more of most runtimes (looking at you legacy Java) just hoard the heap forever because they assume they are the only tenant on the server.

[BatteryMountain]

In C#'s dependency injector you basically have to choose from 3 lifetimes for a class/service: scoped, transient or singletons.

Scoped & transient lifetimes along with the new GC will make the runtime much leaner.

Some application are singleton heavy or misuse the MemoryCache (or wrap it as a singleton... facepalm) - these will still mess the GC situation up.

If you build web/api project it pays dividends to educate yourself on the 3 life times, how the GC works, how async/await/cancellation tokens/disposables work, how MemoryCache work (and when to go out-of-process / other machine aka Redis), how the built-in mechanisms in aspnet works to cache html outputs etc. A lot of developers just wing it and then wonder why they have memory issues.

And for for the dinosaurs: yes we can use the dependency injector in Windows Form, WPF, Console Apps and so on - those packages aren't limited to web projects alone.