I've run into this issue several times now where windows explorer 10 has some sort of conflict with windows search service. This happens on clean installs and more frequently to those that have upgraded from windows 7 or 8 to windows 10.
Here is the quick fix to resolve this:
Ctrl+Alt+Del > Select "Task Manager"
Once task manager opens select the wind and type "w" until it selects "Windows Explorer", right click and end task. This will cause all of your windows explorer items to be removed from the windows interface and you should notice the pc has returned to normal, no longer slow.
If this is the case continue with the next step,
Choose "file" from "Task Manager" then enter "services.msc" and click "ok", now scroll down to "Windows Search" double click and change the startup type to "Disabled" then "Stop" the service.
(please note, this will disable your windows search function)
To restore windows explorer select "file" from the task manager and "run new task" enter "explorer.exe" and click ok. Everything should now be working properly other than "Windows Search" which is now disabled.