greetings all!

i have been configuring a relatively low powered virtual server to serve a php app (a social network that is built using the elgg framework).
i read this page (http://seravo.fi/2013/optimizing-web-server-performance-with-nginx-and-php) about optimising the nginx server and ran through the benchmarking process described there - tweaking various nginx options.

i saw that my site's pages are loading much more slowly than the server in the examples on that linked page - however my server is 1 cpu and 1GB RAM presently.. and the site is https only - so i comprehend that the speed is likely to be slower.

my question is that the best performance graph i saw from my site so far was with this in nginx.conf:

fastcgi_cache_path /var/cache/nginx levels=1:2 keys_zone=microcache:10m max_size=1000m inactive=60m;
open_file_cache max=1000 inactive=20s;
open_file_cache_valid 30s;
open_file_cache_min_uses 2;
open_file_cache_errors on;
keepalive_requests 100000;

gzip_static on;

and my own version of the caching logic that was used in the example on the seravo.fi page - adapted from wordpress to elgg (as best i could with what i know currently). you can view the graph i made of the various configurations i tested here: https://www.infiniteeureka.com/_graphics/img/nginx-graph.png

- the white line is with the tweaked config files + the caching enabled.

however.. what i am not comprehending is why i am not seeing the type of 'full html caching' performance that is shown in the tutorial/guide on seravo.fi.. i was aiming to have the whole page cached - but that is not occurring.
my first thought is that maybe the caching headers are wrongly set.. or not set for some reason..
i have these lines in the config for the site:

location ~* \.(css|js|html|htm)$ {
expires max;
gzip_static on;
log_not_found off;
add_header Pragma "public";
add_header Cache-Control "public";
}
location ~* \.(jpg|jpeg|gif|png|mp3|flv|mov|avi|3pg|swf|ico|woff|cur|htc|webm|ttf)$ {
expires max;
gzip_static off;
log_not_found off;
add_header Pragma "public";
add_header Cache-Control "public";
}

if anyone has any tips i will glady experiment with them..
once i have this perfected i will share with the elgg community at least to get them more inspired to use nginx.

my thanks in advance for any help here.