You may have the same issue with preferences that I did in windows. Try entering opera://config in the address bar, then it is under Privacy & Security about half way down. I don't see the Turbo option on the Mac version (it is mutually exclusive with VPN), so that should not be your problem.
Bookmarks are stored in the profile in a file named "Bookmarks", with no extension name.
You need to install an extension to export bookmarks, since Opera will not do that itself. I am using V7 Bookmarks, which is a pretty good extension.
My vote also goes to trackers, which incidentally also usually cause a big speedup when blocked :). As @zalex108 says, you can disable EasyPrivacy in Opera's Preferences to see if that was it.