Резкое повышение потребления оперативной памяти при скачивании файла с сервера

#user  nobody;
worker_processes  1;

#error_log  logs/error.log;
#error_log  logs/error.log  notice;
#error_log  logs/error.log  info;

#pid        logs/nginx.pid;


events {
    worker_connections  1024;
}


http {
    include       mime.types;
    default_type  application/octet-stream;

    #log_format  main  '$remote_addr - $remote_user [$time_local] "$request" '
    #                  '$status $body_bytes_sent "$http_referer" '
    #                  '"$http_user_agent" "$http_x_forwarded_for"';

    #access_log  logs/access.log  main;

    sendfile        on;
    #tcp_nopush     on;

    #keepalive_timeout  0;
    keepalive_timeout  65;

    #gzip  on;

    server {
        listen       example.com:80;
        server_name  example.com;

        #charset koi8-r;

        #access_log  logs/host.access.log  main;

        location / {
            root   /path_to_example.com/;
            index  index.html index.htm index.php;
        }

        # proxy the PHP scripts to Apache listening on example.com:8080
        #
        location ~ \.php$ {
            proxy_pass   http://example.com:8080;
        }


    # another virtual host using mix of IP-, name-, and port-based configuration
    #
    server {
        listen       files.example.com:80;
        server_name  example.com;

        #charset koi8-r;

        #access_log  logs/host.access.log  main;

        location / {
            root   /path_to_files.example.com/;
        }

}

        location / {
            root   /path_to_example.com/;
            index  index.html index.htm index.php;
        }

        location / {
            root   /path_to_files.example.com/;
        }