Dave said:
safe mode is much faster. I've disabled the features you mentioned
and it seems to help significantly.
Safe mode will be faster because the installed (and enabled) add-ons for
Outlook do not get also loaded; however, that means you lose the
functionality afforded by those add-ons. So you need to look at the
list of add-ons to determine which ones you really need or want.
I suspect blocking on external content solved your problem (you weren't
clear what you changed to get rid of the delay). You should be doing
that all the time as it represents a privacy vulnerability to let anyone
use a web beacon to see when you happen to open an HTML-formatted email.
Plus it means your host has to connect to some other other host to
retrieve that external content so responsiveness in your e-mail client
is affected by the responsiveness of the other-content site. If they're
slow then so are you. If you block the external content, a yellow
infobar will tell you about the block. If you decide that you want to
see that external content, you have a choice on a per e-mail basis
rather than defaulting to always retrieving that external content.