When starting Office, Oracle Smart View for Office performs various security checks at startup, including checks on all the installed extensions. Internet connectivity is required in order to perform these checks.
Without internet connectivity, the security checks on extensions cannot be carried out and Office applications will be very slow to launch.
You may disable extensions in order to improve Office startup time, but you will lose the functionality related to those extensions, even if you are still able to connect to data providers through your company's intranet.
Oracle recommends verifying that you can connect to the internet when starting Office with Smart View installed.