Using nginx as proxy server is very slow, but it is very fast if using nginx in docker! Why?

Using nginx as proxy server is very slow, but it is very fast if using nginx in docker! Why?

app.yml

templates:
  #- "templates/postgres.template.yml"
  - "templates/redis.template.yml"
  - "templates/web.template.yml"
  - "templates/sshd.template.yml"
  - "templates/web.ratelimited.template.yml"
## Uncomment these two lines if you wish to add Lets Encrypt (https)
  #- "templates/web.ssl.template.yml"
  #- "templates/web.letsencrypt.ssl.template.yml"
  - "templates/web.socketed.template.yml"

expose:
  #- "8080:80"   # http
  #- "444:443" # https

params:
  db_default_text_search_config: "pg_catalog.english"

  ## Set db_shared_buffers to a max of 25% of the total memory.
  ## will be set automatically by bootstrap based on detected RAM, or you can override
  db_shared_buffers: "780MB"

  ## can improve sorting performance, but adds memory usage per-connection
  # db_work_mem: "512MB"

  ## Which Git revision should this container use? (default: tests-passed)
  version: stable

env:
  # 数据库配置
  DISCOURSE_DB_USERNAME: ****
  DISCOURSE_DB_PASSWORD: ***
  DISCOURSE_DB_HOST: ***
  DISCOURSE_DB_NAME: ***
  DISCOURSE_DB_PORT: ***
  DISCOURSE_DB_BACKUP_PORT: ***

  LANG: zh_CN.UTF-8
  DISCOURSE_DEFAULT_LOCALE: zh_CN

  ## How many concurrent web requests are supported? Depends on memory and CPU cores.
  ## will be set automatically by bootstrap based on detected CPUs, or you can override
  UNICORN_WORKERS: 2

nginx config

server {
    listen 80; listen [::]:80;
    server_name my.web.org;

    return 301 https://$host$request_uri;
}

server {
    listen 443 ssl http2;  listen [::]:443 ssl http2;
    server_name minetest.cosoc.org;

    ssl_certificate      /var/discourse/shared/standalone/ssl/my.web.org.cer;
    ssl_certificate_key  /var/discourse/shared/standalone/ssl/my.web.org.key;
    ssl_session_tickets off;
    http2_idle_timeout 5m; # up from 3m default


location / {
        proxy_pass http://unix:/var/discourse/shared/standalone/nginx.http.sock;
        proxy_set_header Host $http_host;
        proxy_http_version 1.1;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto https;
        proxy_set_header X-Real-IP $remote_addr;
    }

Why is nginx acting so slowly??? But it’s fast when you don’t use it!!