I encountered some issues too after moving to Windows 11, especially with startup times and general sluggishness. One effective step I took was to delve into the Task Manager and limit the programs that automatically run at startup. You might be surprised how many applications are set to launch when you turn on your computer, which can significantly slow everything down.
Another helpful approach is to adjust for best performance under system properties. You can do this by typing "Adjust the appearance and performance of Windows" in the search bar. From there, choose 'Adjust for best performance' and apply the changes. It strips down some visual effects which can free up resources.
And here's a light-hearted joke since we're talking about upgrades: Why did the computer go to therapy? Because it had too many unresolved issues after an upgrade! Hope these tips assist you smooth out those pesky lags!