Hi there,
If the internet is slow in Internet Explorer 11, Microsoft has confirmed that this is a problem in the browser itself. To fix this issue, install the most recent cumulative security update for Internet Explorer. To do this, go to Microsoft Update. Slow browsing when you use Roaming User Profiles with Folder Redirection in Internet Explorer 11 https://support.microsoft.com/en-us/topic/slow-browsing-when-you-use-roaming-user-profiles-with-folder-redirection-in-internet-explorer-11-90607206-f545-d19b-baac-8a40e5601b25
You can also try Managing User Profile Service slow link detection. Windows User Profile Service can use slow link detection to determine whether to download a roaming user profile to the client computer when the user signs in.https://dori-uw-1.kuma-moon.com/en-us/troubleshoot/windows-server/user-profiles-and-logon/manage-profile-service-slow-link-detection
The below thread discusses the same issue and you can try out some troubleshooting steps from this and see if that helps you to sort the Issue.https://social.technet.microsoft.com/forums/windows/en-US/4c30e1a3-2cb8-4d10-be57-fed9caa4a167/windows-10-experiencing-very-slow-login-times-in-domain-environment?forum=win10itprohardware
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