Super slow boot up

After recent update, my mac has been booting extremely slow, up to 40 minutes to get to log in screen. Then once logged in, it does load the background image and files on the desktop but not the images of the files, just the names with generic icons. When I tried to go to system preferences to see what's in the startup, it just spins to load system preferences. I lost my patience and rebooted into safe mode. It was a bit faster but very similar performance. i never actually got to system preference screen because it was taking super ling to load anything. I reset PRAM but it didnt help either. Any ideas?