This is one where I do see a pretty big difference:
$ time curl
https://pagure.io/static/vendor/emojione/emojione.sprites.png -o /dev/null
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 2408k 100 2408k 0 0 602k 0 0:00:04 0:00:04 --:--:-- 556k
curl
https://pagure.io/static/vendor/emojione/emojione.sprites.png -o 0.10s user 0.05s
system 3% cpu 4.432 total
With the entry in /etc/hosts:
$ time curl
https://pagure.io/static/vendor/emojione/emojione.sprites.png -o /dev/null
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 2408k 100 2408k 0 0 160k 0 0:00:15 0:00:15 --:--:-- 210k
curl
https://pagure.io/static/vendor/emojione/emojione.sprites.png -o 0.13s user 0.12s
system 1% cpu 15.626 total
Pierre