I want TB to load 100% of the my mail in the background, including all pictures and attachments when my laptop has WiFi connection.
Right now when opening a new message, the text shows instantly, but there's delay when until the pictures show up.
When I reopen the same message the pictures instantly show.

I don't even like that when reading on my desktop with a permanent connection. Even less on my laptop which I also use when I have no internet.
So it's important everything is prefetched.

How do I configure that?