Say, do the boilerplate images always present on every Mediawiki page
have enough Expires and/or etc. headers to keep them cached around the
network for a long time? (Can't tell here offline with images turned
off anyway). Seems like optimizing that would need messing with the
apache etc. configuration as it is beyond what one can do with php as
they are <img src=...>. I.e., well at least we will send "304 not
modified", as we (standard Mediawiki installation) are not going to go
further to eliminate them asking in the first place... but as you can
see, what do I know.