Ngnix is very slow - nginx

Question

I configured ngnix but it is very slow. Sometimes when I hit reload assets are pending until it starts to download them. I noticed that after few consecutive reloads of the page it start to hang, pending assets and slows down. Is there something wrong with my configuration? I deploy my app to Heroku and use ngnix in front.
daemon off;
worker_processes <%= ENV['NGINX_WORKERS'] || 4 %>;
worker_rlimit_nofile 10000;
events {
# optmized to serve many clients with each thread
use epoll;
# if accept_mutex is enabled, worker processes will accept new connections by turn. Otherwise, all worker processes will be notified about new connections, and if volume of new connections is low, some of the worker processes may just waste system resources.
accept_mutex on;
multi_accept on;
worker_connections 1024;
}
# error logs
error_log logs/nginx/error.log;
error_log logs/nginx/error_extreme.log emerg;
error_log logs/nginx/error_debug.log debug;
error_log logs/nginx/error_critical.log crit;
http {
charset utf-8;
include mime.types;
default_type application/octet-stream;
log_format l2met 'measure#nginx.service=$request_time request_id=$http_x_request_id';
access_log logs/nginx/access.log l2met;
# # - Basic Settings
sendfile on;
tcp_nopush on;
tcp_nodelay on;
types_hash_max_size 2048;
# # - Enable open file cache
open_file_cache max=1000 inactive=20s;
open_file_cache_valid 30s;
open_file_cache_min_uses 2;
open_file_cache_errors on;
# # - Configure buffer sizes
client_body_buffer_size 16k;
client_header_buffer_size 1k;
# # - Responds with 413 http status ie. request entity too large error if this value exceeds
client_max_body_size 8m;
large_client_header_buffers 2 1k;
# # - Configure Timeouts
client_body_timeout 12;
client_header_timeout 12;
# # - Use a higher keepalive timeout to reduce the need for repeated handshake
keepalive_timeout 300;
# # - if the request is not completed within 10 seconds, then abort the connection and send the timeout errror
send_timeout 10;
# # - Hide nginx version information
server_tokens off;
# # - Dynamic gzip compression
gzip on;
gzip_http_version 1.0;
gzip_disable "msie6";
gzip_vary on;
gzip_min_length 20;
gzip_buffers 4 16k;
gzip_comp_level 3;
gzip_proxied any;
#Turn on gzip for all content types that should benefit from it.
gzip_types application/ecmascript;
gzip_types application/javascript;
gzip_types application/json;
gzip_types application/pdf;
gzip_types application/postscript;
gzip_types application/x-javascript;
gzip_types image/svg+xml;
gzip_types text/css;
gzip_types text/csv;
gzip_types text/javascript;
gzip_types text/plain;
gzip_types text/xml;
map $http_upgrade $connection_upgrade {
default upgrade;
'' close;
}
#proxying requests to other servers
upstream nodebeats {
server unix:/tmp/nginx.socket max_fails=3 fail_timeout=30s;
keepalive 32;
}
server {
listen <%= ENV['PORT'] %>;
server_name _;
root "/app/";
location / {
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header Host $http_host;
proxy_redirect off;
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
proxy_pass http://nodebeats;
}
location ~* \.(js|css|jpg)$ {
root "/app/src/dist";
add_header Pragma public;
add_header Cache-Control public;
expires 1y;
gzip_static on;
gzip off;
gzip_http_version 1.0;
gzip_disable "msie6";
gzip_vary on;
gzip_min_length 20;
gzip_proxied any;
}
}
}
EDIT
Ok. I found out what setting is causing this. It is proxy_read_timeout which is by default 60 seconds. If i put it to 1 second, i can reload page any number of times I want and it always refreshes quickly. But why?
That is supposed to be time that nginx waits server to respond. If I get back response and reload the page, why does it stale? Isn't timeout supposed to be restarted and wait for response again?