How would you investigate a Windows computer that is slow immediately after sign-in?

Determine whether the delay affects one user or every user and whether it is new. Inspect startup applications, CPU, memory, disk activity, and relevant event logs. Check profile loading, logon scripts, endpoint protection activity, available storage, and recent updates. Compare a clean test profile or controlled startup when appropriate, documenting changes so they can be reversed. Do not disable security tools indiscriminately. Establish a baseline and verify the improvement after each targeted change rather than deleting files or modifying registry settings without a supported reason.