c0nw0nk Wrote:
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> error_log logs/error.log crit;
>
> Is my current setting should i change it to debug ?

No option is required to get error messages about backend issues.

Remove that first server {} block with the return 200, for fcgi try this;

fastcgi_pass web_rack;
fastcgi_index index.php;
include fastcgi_params;
keepalive_timeout 600;
keepalive_requests 500;
proxy_http_version 1.1;
proxy_ignore_client_abort on;
fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
fastcgi_keep_conn on;
expires 10s;

When you experience a slow page what are the php-cgi processes / mysql doing ? use processexplorer to find out.

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nginx for Windows http://nginx-win.ecsds.eu/