We are using nginx as reverse proxy. There are 4 servers (1x nginx, 2x uWSGI, 1x DB + Memcached). One user told me some time ago, that he has for 3 months problems with loading speed of website. Every request takes 5-10 secs, when for me it takes less than second. What can cause problem? When I did test, and give him access to other IP but NATed to same local address:port, he told me that it's faster, but not yet fast enough.
Our structure - Network -> NAT external IP to internal -> nginx.