Coenberht

https://3d-train-studio.uk has an English speaker's fine tuned translation of the manual.

Use the Task Manager app to see if anything else is going on. Downloading or installing updates, any file syncing services, such as Dropbox or Google One, virus scans and other background apps. Microsoft Edge can update itself even if updates are turned off and even if you don't use Edge. Windows does not ask for your consent to do these things. Game mode can be a bit hit and miss.