Orbited proxied by nginx hangs web traffic for particular user

[Szymon]

We are using nginx -> Orbited for long-polling, nginx -> uwsgi for web
content (AJAX-driven), and nginx for static files. Problem is, when user
open more than, dunno, about 6-7 tabs in browser. Then, traffic for user
(and just for him) just hangs. All new requests takes too long. Is there
particular config option in nginx or Linux that limits these
connections? Or there is problem with something else?

Below is our config, server {} section.

listen 192.168.1.1;
server_name foo;

client_max_body_size 10m;
client_body_buffer_size 128k;

access_log /var/log/nginx/deweloperski.access_log main;
error_log /var/log/nginx/deweloperski.error_log crit;

keepalive_timeout 30;

location /poll {

    proxy_pass http://127.0.0.1:15000/;
    proxy_redirect off;
    proxy_set_header Host $host;
    proxy_set_header X-Real-IP $remote_addr;
    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    client_max_body_size 100m;
    client_body_buffer_size 128k;
    proxy_connect_timeout 90;
    proxy_send_timeout 90;
    proxy_read_timeout 90;
    proxy_buffer_size 4k;
    proxy_buffers 4 32k;
    proxy_busy_buffers_size 64k;
    proxy_temp_file_write_size 64k;

}

location /poll/tcp {

    proxy_pass http://127.0.0.1:15000/tcp;
    proxy_buffering off;
    tcp_nodelay on;

}

location / {

    uwsgi_pass deweloperski;
    add_header Cache-Control no-store;
    add_header Vary *;
    expires epoch;
    include uwsgi.params;
    include uwsgi.conf;

}

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,206154,206154#msg-206154