If your willing to reformat then why not duel drive it, put a second faster drive (SSD)in and put the OS on the SSD and use the old drive for storage, you don't have to disturb the original drive file structure . Use a [https://www.magicaljellybean.com/keyfinder/|keyfinder] to gleen the OEM key from the system and then install your windows ten on the SSD and install the key . Once everything is up and running to your satisfaction delete the old windows system files from old hard drive for more storage space. Another thing you may want to look at is , when you upgraded from 7 to 8 and then to 10 did you do it with clean installs or by laying one OS over top the previous If you just installed one over the other there is probably a lot of left overs slowing you down .[https://www.cnet.com/how-to/how-to-delete-the-windows-old-folder-from-windows-10/|This should help with the cleanup]