Windows 11 has become slow after startup

Because the delay occurs after sign-in, while the taskbar and File Explorer are unresponsive, the bottleneck is probably a startup app, service, storage activity, or profile initialization rather than firmware boot. Open Task Manager > Startup apps, sort by Startup impact, and disable only nonessential entries. Restart and compare the time from sign-in to a usable desktop. During the delay, check Task Manager’s Processes and Performance tabs for disk, CPU, or memory use and note the responsible process. Ensure the system drive has free space, then install Windows updates and manufacturer chipset and storage drivers. If no process is obvious, perform a clean boot and re-enable services in groups to isolate the offender. Run DISM /Online /Cleanup-Image /RestoreHealth and then sfc /scannow from an elevated terminal. Finally, test a new local account. Avoid registry cleaners or broad service-disabling scripts because they can hide the cause or remove required components.