Absolutely! Implementing **full-page caching with Nginx** is one of the most powerful ways to dramatically boost WordPress performance, especially for **high-traffic sites** like yours (1k sustained users).

This guide assumes you're using:

- Nginx (not Apache)
- PHP-FPM
- WordPress
- Linux (Ubuntu/Debian)
---

## 🔧 Step-by-Step: Full Page Caching with Nginx (FastCGI Cache)

---

### ✅ 1. **Prepare Directories**

Create a directory for cached pages:

```bash
sudo mkdir -p /var/cache/nginx/wordpress
sudo chown -R www-data:www-data /var/cache/nginx
```

---

### 🧠 2. **Understand the Cache Key**

Nginx will cache based on:
- URI
- Host
- Request method (GET/POST)
- Cookies (important for logged-in vs public users)

---

### ⚙️ 3. **Nginx Configuration**

Open your Nginx server block (e.g., `/etc/nginx/sites-available/yourdomain.com`) and make the following changes:

#### a. Enable the cache zone

Add this at the top of the file (outside the server block):

```nginx
fastcgi_cache_path /var/cache/nginx/wordpress levels=1:2 keys_zone=WORDPRESS:100m inactive=60m use_temp_path=off;
fastcgi_cache_key "$scheme$request_method$host$request_uri";
```

#### b. Inside your `server {}` block

Insert the following:

```nginx
set $no_cache 0;

# Don't cache POST requests or certain URIs
if ($request_method = POST) {
    set $no_cache 1;
}
if ($query_string != "") {
    set $no_cache 1;
}

# Don't cache logged-in users or recent commenters
if ($http_cookie ~* "comment_author_|wordpress_logged_in_|wp-postpass_") {
    set $no_cache 1;
}
```

#### c. Inside your `location ~ \.php$` block

Modify it to include FastCGI caching:

```nginx
location ~ \.php$ {
    include snippets/fastcgi-php.conf;
    fastcgi_pass unix:/run/php/php8.2-fpm.sock;

    fastcgi_cache WORDPRESS;
    fastcgi_cache_bypass $no_cache;
    fastcgi_no_cache $no_cache;
    fastcgi_cache_valid 200 301 302 60m;

    add_header X-FastCGI-Cache $upstream_cache_status;

    fastcgi_cache_use_stale error timeout invalid_header http_500;
}
```

This will:
- Cache pages for 60 minutes
- Avoid caching for logged-in users and POST requests
- Add a response header like `X-FastCGI-Cache: HIT` or `MISS`

---

### 💡 4. **Purge Cache (Optional)**

Nginx FastCGI Cache does not automatically purge pages when WordPress content is updated.

**Options:**

- Use [`nginx-cache-purge`](https://github.com/FRiCKLE/ngx_cache_purge) module (requires recompiling Nginx)
- Use a plugin like [**Nginx Cache**](https://wordpress.org/plugins/nginx-helper/) which works well with Redis or FastCGI:
  ```php
  define('RT_WP_NGINX_HELPER_CACHE_PATH', '/var/cache/nginx/wordpress');
  define('RT_WP_NGINX_HELPER_LOG_PATH', '/var/log/nginx/wordpress-helper.log');
  ```

---

### ✅ 5. **Reload Nginx**

```bash
sudo nginx -t
sudo systemctl reload nginx
```

---

## 🧪 6. **Test It**

- Open a browser → Visit your homepage
- Run:
  ```bash
  curl -I https://yourdomain.com
  ```

You should see:
```http
X-FastCGI-Cache: HIT
```

Try again after logging in to WordPress. You should see:
```http
X-FastCGI-Cache: BYPASS
```

---

## 🔍 7. **Optional: Clear Cache Manually**
```bash
sudo rm -rf /var/cache/nginx/wordpress/*
```

---

## 🚀 Performance Gains

| Without Cache       | With Nginx FastCGI Cache |
|---------------------|--------------------------|
| 300–800ms TTFB      | 50–100ms TTFB            |
| High CPU/PHP usage  | Very low CPU usage       |
| DB load under traffic| Minimal DB activity      |