Probably a cache thing. Win11 precaches a lot of stuff if you hover over it or have excess RAM. It's not as smart as SuperFetch and ReadyBoost (with an HDD) was but it's still doing similar things.
You shouldn't need to cache a calculator app to make it load quickly - it opened instantly on a machine running Windows 3.0 with 2MB RAM.
How big is the calculator app on Windows 11 that you need to cache it in RAM? On macOS, the calculator app is 6 MB. And that's containing both x64 and ARM code. How long does it take a modern SSD (6 GB/s?) to read that?