Nginx server very slow - nginx

Question

I have two joomla websites on a raspberry pi with nginx server.
One of them (the default one: www.sauvtag.com), is very very slow on the first request.
I don't know why. I'm a newbie on nginx.
Could you please help me?
here is my site-available configuration
# You may add here your
# server {
# ...
# }
# statements for each of your virtual hosts to this file
##
# You should look at the following URL's in order to grasp a solid understanding
# of Nginx configuration files in order to fully unleash the power of Nginx.
# http://wiki.nginx.org/Pitfalls
# http://wiki.nginx.org/QuickStart
# http://wiki.nginx.org/Configuration
#
# Generally, you will want to move this file somewhere, and start with a clean
# file but keep this around for reference. Or just disable in sites-enabled.
#
# Please see /usr/share/doc/nginx-doc/examples/ for more detailed examples.
##
server {
listen 80 default_server; ## listen for ipv4; this line is default and implied
# listen [::]:80; ## listen for ipv6
root /var/www/sauvtag.com/;
index index.html index.htm index.php;
# Make site accessible from http://localhost/
server_name sauvtag.com www.sautag.com;
location / {
# First attempt to serve request as file, then
# as directory, then fall back to displaying a 404.
expires 1d;
try_files $uri $uri/ /index.php?$args;
# Uncomment to enable naxsi on this location
# include /etc/nginx/naxsi.rules
}
location /doc/ {
alias /usr/share/doc/;
autoindex on;
allow 127.0.0.1;
allow ::1;
deny all;
}
#cache navigateur
location ~* \.(js|css|png|jpg|jpeg|JPG|gif|ico|woff)$ {
expires 7d;
}
# Only for nginx-naxsi used with nginx-naxsi-ui : process denied requests
#location /RequestDenied {
# proxy_pass http://127.0.0.1:8080;
#}
#error_page 404 /404.html;
# redirect server error pages to the static page /50x.html
#
#error_page 500 502 503 504 /50x.html;
#location = /50x.html {
# root /usr/share/nginx/www;
#}
# pass the PHP scripts to FastCGI server listening on 127.0.0.1:9000
#
location ~ \.php$ {
fastcgi_split_path_info ^(.+\.php)(/.+)$;
# # NOTE: You should have "cgi.fix_pathinfo = 0;" in php.ini
#
# # With php5-cgi alone:
# fastcgi_pass 127.0.0.1:9000;
# # With php5-fpm:
fastcgi_pass unix:/var/run/php5-fpm.sock;
fastcgi_index index.php;
include fastcgi_params;
fastcgi_cache nginxcache;
fastcgi_cache_key $host$request_uri;
fastcgi_cache_valid any 2h;
fastcgi_cache_use_stale off;
}
# deny access to .htaccess files, if Apache's document root
# concurs with nginx's one
#
location ~ /\.ht {
deny all;
}
}
# another virtual host using mix of IP-, name-, and port-based configuration
#
#server {
# listen 8000;
# listen somename:8080;
# server_name somename alias another.alias;
# root html;
# index index.html index.htm;
#
# location / {
# try_files $uri $uri/ =404;
# }
#}
# HTTPS server
#
#server {
# listen 443;
# server_name localhost;
#
# root html;
# index index.html index.htm;
#
# ssl on;
# ssl_certificate cert.pem;
# ssl_certificate_key cert.key;
#
# ssl_session_timeout 5m;
#
# ssl_protocols SSLv3 TLSv1;
# ssl_ciphers ALL:!ADH:!EXPORT56:RC4+RSA:+HIGH:+MEDIUM:+LOW:+SSLv3:+EXP;
# ssl_prefer_server_ciphers on;
#
# location / {
# try_files $uri $uri/ =404;
# }
#}
here is also my nginx configuation file
user www-data;
worker_processes 4;
pid /var/run/nginx.pid;
events {
worker_connections 768;
# multi_accept on;
}
http {
##
# Basic Settings
##
sendfile on;
tcp_nopush on;
tcp_nodelay on;
keepalive_timeout 65;
types_hash_max_size 2048;
# server_tokens off;
client_max_body_size 3M;
server_names_hash_bucket_size 64;
# server_name_in_redirect off;
include /etc/nginx/mime.types;
default_type application/octet-stream;
##cache config fast cgi
fastcgi_cache_path /var/cache/nginx levels=1:2 keys_zone=nginxcache:10m inactive=2h max_size=1g;
##
# Logging Settings
##
access_log /var/log/nginx/access.log;
error_log /var/log/nginx/error.log;
##
# Gzip Settings
##
gzip on;
gzip_disable "msie6";
gzip_vary on;
gzip_proxied any;
gzip_comp_level 6;
gzip_buffers 16 8k;
gzip_http_version 1.1;
gzip_types text/plain text/css application/json application/x-javascript text/xml application/xml application/xml+rss text/javascript;
gzip_static on;
##
# nginx-naxsi config
##
# Uncomment it if you installed nginx-naxsi
##
#include /etc/nginx/naxsi_core.rules;
##
# nginx-passenger config
##
# Uncomment it if you installed nginx-passenger
##
#passenger_root /usr;
#passenger_ruby /usr/bin/ruby;
##
# Virtual Host Configs
##
include /etc/nginx/conf.d/*.conf;
include /etc/nginx/sites-enabled/*;
}
#mail {
# # See sample authentication script at:
# # http://wiki.nginx.org/ImapAuthenticateWithApachePhpScript
#
# # auth_http localhost/auth.php;
# # pop3_capabilities "TOP" "USER";
# # imap_capabilities "IMAP4rev1" "UIDPLUS";
#
# server {
# listen localhost:110;
# protocol pop3;
# proxy on;
# }
#
# server {
# listen localhost:143;
# protocol imap;
# proxy on;
# }
#}

Answer 1

Hi every one first of all i'm running joomla 3.4 on a raspberry b+. I use a class 10 Sd card.
On joomla I use:
-communiquer builer
-jch-optimize (which minify HTML and css)
The request which is very very slow is the first get request (for the HTML)
Maybe I should use a usb2 hard drive for the /www/ directory.
Note: I have another website on this raspberry (also running on joomla) which works perfecty.