If the Windows 11 Start Menu is really slow to display search results, try resetting the Client WebExperience and Client CBS apps. Run the following from an elevated Powershell prompt:

Get-AppxPackage -AllUsers *MicrosoftWindows.Client.WebExperience* | Reset-AppxPackage 
Get-AppxPackage *MicrosoftWindows.Client.WebExperience* | Reset-AppxPackage
Get-AppxPackage *MicrosoftWindows.Client.CBS* | Reset-AppxPackage

Windows 11 search bar has recently been very slow
byu/Uwubabys inWindowsHelp