I just upgraded my both machines from Windows 10 to Windows 11. I find out that initial memory after boot up has used around 6GB memory. You can view it from Task Manager.
Here is my fine-tuning and success to reduce around 3GB of memory.
1. Disable start-up program. Microsoft runs a few applications in the background.
-> Use Task Manager | Start up | Disable unwanted programs such as Cortana, MS Team, Onedrive
2. Go to System Properties | Advanced Tab | Settings
-> Under Visual Effect, set Adjust for best performance
3. Modify the registry key
-> Type Regedit
-> Navigate to Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management
Set ClearPageFileAtShutDown to 1
Restart the machine
Check again the memory usage using Task Manager. Do you get from 6GB to around 3GB?
Hope this trick helps to reduce your memory usage when upgrading to Windows 11.
Note: These settings are applicable after the upgrade to Windows 11 or the initial setup. Not apply when you install more program and run more on start up application.