Command + f hangs Finder
Based upon your descriptions, it appears to be an active bug related to smart search and regular search.

On page two of that discussion, one of the posters stated the following:


  Here is what finally fixed for me. I went in mail.app (whose search
  was totally misbehaving too), and I rebuild all the mailboxes in my
  accounts. (Select all the folders, "Folder" menu, "rebuild") When this
  finished, I rebuilt my index again, restarted and... it is working
  like a charm since then!