API endpoint performance - node.js

Question

I am attempting to benchmark the perf of my rest API endpoint. It's a node/mongdb endpoint with a pretty nasty aggregate query - a few unwraps, groups and a lookup. I am using Apache Bench (ab) to test it perf under 100 concurrency 1000 times. My issue: I am getting different results based on where I run the ab test:
localhost:3000/api_endpoint/ using ngrok to tunnel it = I am
getting around 50 requests per second.
Running the test on the
production app server directly where the app is hosed I am seeing
6000 requests per second.
Running it from my web server/reverse proxy I am seeing similarly 5000reqs per second -if I use a relative path to the API.
NOW: If I run the same test on the web server
but this time use the domain name instead or run it from local dev
machine but hitting the domain, now it drops to 9 requests per
second.
What can I deduce this? To me, It seems the query must not be that nasty if I am getting such high perf when I hit it directly. It seems I either have something configured wrong in my nginx.conf file for handing my domain requests or there is a DNS resolution problem? Its an exotic TLD (.ly) could that be it? Where should I look?
Edit: Adding my nginx.conf file for analysis:
user www-data;
worker_processes 1;
#error_log /log/nginx/error.log;
pid /run/nginx.pid;
# Load dynamic modules. See /usr/share/nginx/README.dynamic.
#include /usr/share/nginx/modules/*.conf;
events {
worker_connections 1024;
}
http {
#optimizations per digitalOcean
client_body_buffer_size 10K;
client_header_buffer_size 1k;
client_max_body_size 8m;
large_client_header_buffers 2 1k;
client_body_timeout 12;
client_header_timeout 12;
keepalive_timeout 15;
send_timeout 10;
#compression
gzip on;
gzip_disable "msie6";
gzip_proxied any;
gzip_comp_level 6;
gzip_buffers 16 8k;
gzip_http_version 1.1;
gzip_min_length 256;
gzip_proxied expired no-cache no-store private auth;
gzip_types text/plain application/x-javascript text/xml text/css application/xml application/json text/xml application/xml+rss application/javascript text/javascript application/vnd.ms-fontobject application/x-font-ttf font/opentype image/svg+xml image/x-icon;
access_log off;
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 /var/log/nginx/access.log main;
sendfile on;
tcp_nopush on;
tcp_nodelay on;
types_hash_max_size 2048;
include /etc/nginx/mime.types;
default_type application/octet-stream;
# Load modular configuration files from the /etc/nginx/conf.d directory.
# See http://nginx.org/en/docs/ngx_core_module.html#include
# for more information.
include /etc/nginx/conf.d/*.conf;
#redirect to https
server {
server_name www.staq.ly staq.ly getstackrank.com www.getstackrank.com;
return 301 https://staq.ly;
}
server {
listen 80;
listen 443 ssl;
server_name staq.ly;
ssl_certificate /etc/nginx/ssl/staqly.crt;
ssl_certificate_key /etc/nginx/ssl/staqly.key;
root /var/local;
location ~ ^/(sitemap.xml) {
}
location ~ ^/(robots.txt) {
}
location ~ ^/(googlee828ea2f1ef594b3.html) {
}
location / {
try_files $uri #prerender;
}
location #prerender {
proxy_set_header X-Prerender-Token XXXXXXXX;
set $prerender 0;
if ($http_user_agent ~* "baiduspider|twitterbot|facebookexternalhit|rogerbot|linkedinbot|embedly|quora link preview|showyoubot|outbrain|pinterest|slackbot|vkShare|W3C_Validator") {
set $prerender 1;
}
if ($args ~ "_escaped_fragment_") {
set $prerender 1;
}
if ($http_user_agent ~ "Prerender") {
set $prerender 0;
}
if ($uri ~* "\.(js|css|xml|less|png|jpg|jpeg|gif|pdf|doc|txt|ico|rss|zip|mp3|rar|exe|wmv|doc|avi|ppt|mpg|mpeg|tif|wav|mov|psd|ai|xls|mp4|m4a|swf|dat|dmg|iso|flv|m4v|torrent|ttf|woff|svg|eot)") {
set $prerender 0;
}
#resolve using Google's DNS server to force DNS resolution and prevent caching of IPs
resolver 8.8.8.8;
if ($prerender = 1) {
#setting prerender as a variable forces DNS resolution since nginx caches IPs and doesnt play well with load balancing
set $prerender "service.prerender.io";
rewrite .* /$scheme://$host$request_uri? break;
proxy_pass http://$prerender;
}
if ($prerender = 0) {
# rewrite .* /index.ejs break; # Throw away the path because this is a single page web app with only an index.html
proxy_pass http://10.132.126.36:3000;
}
}
}
}