wagtail/docs/advanced_topics/performance.md

# Performance

Wagtail is designed for speed, both in the editor interface and on the front-end, but if you want even better performance or you need to handle very high volumes of traffic, here are some tips on eking out the most from your installation.

## Editor interface

We have tried to minimise external dependencies for a working installation of Wagtail, in order to make it as simple as possible to get going. However, a number of default settings can be configured for better performance:

### Cache

We recommend [Redis](https://redis.io/) as a fast, persistent cache. Install Redis through your package manager (on Debian or Ubuntu: `sudo apt-get install redis-server`), add `django-redis` to your `requirements.txt`, and enable it as a cache backend:

```python
CACHES = {
    'default': {
        'BACKEND': 'django_redis.cache.RedisCache',
        'LOCATION': 'redis://127.0.0.1:6379/dbname',
        # for django-redis < 3.8.0, use:
        # 'LOCATION': '127.0.0.1:6379',
        'OPTIONS': {
            'CLIENT_CLASS': 'django_redis.client.DefaultClient',
        }
    }
}
```

### Caching image renditions

If you define a cache named 'renditions' (typically alongside your 'default' cache),
Wagtail will cache image rendition lookups, which may improve the performance of pages
which include many images.

```python
CACHES = {
    'default': {...},
    'renditions': {
        'BACKEND': 'django.core.cache.backends.memcached.MemcachedCache',
        'LOCATION': '127.0.0.1:11211',
        'TIMEOUT': 600,
        'OPTIONS': {
            'MAX_ENTRIES': 1000
        }
    }
}
```

### Search

Wagtail has strong support for [Elasticsearch](https://www.elastic.co) - both in the editor interface and for users of your site - but can fall back to a database search if Elasticsearch isn't present. Elasticsearch is faster and more powerful than the Django ORM for text search, so we recommend installing it or using a hosted service like [Searchly](http://www.searchly.com/).

For details on configuring Wagtail for Elasticsearch, see [](wagtailsearch_backends_elasticsearch).

### Database

Wagtail is tested on PostgreSQL, SQLite and MySQL. It may work on some third-party database backends as well, but this is not guaranteed. We recommend PostgreSQL for production use.

### Templates

The overhead from reading and compiling templates adds up. Django wraps its default loaders with [cached template loader](django.template.loaders.cached.Loader) which stores the compiled `Template` in memory and returns it for subsequent requests. The cached loader is automatically enabled when `DEBUG` is `False`. If you are using custom loaders, update your settings to use it:

```python
TEMPLATES = [{
    'BACKEND': 'django.template.backends.django.DjangoTemplates',
    'DIRS': [os.path.join(BASE_DIR, 'templates')],
    'OPTIONS': {
        'loaders': [
            ('django.template.loaders.cached.Loader', [
                'django.template.loaders.filesystem.Loader',
                'django.template.loaders.app_directories.Loader',
                'path.to.custom.Loader',
            ]),
        ],
    },
}]
```

## Public users

(caching_proxy)=

### Caching proxy

To support high volumes of traffic with excellent response times, we recommend a caching proxy. Both [Varnish](https://varnish-cache.org/) and [Squid](http://www.squid-cache.org/) have been tested in production. Hosted proxies like [Cloudflare](https://www.cloudflare.com/) should also work well.

Wagtail supports automatic cache invalidation for Varnish/Squid. See [](frontend_cache_purging) for more information.

### Image attributes

For some images, it may be beneficial to lazy load images, so the rest of the page can continue to load. It can be configured site-wide [](adding_default_attributes_to_images) or per-image [](image_tag_alt). For more details you can read about the [`loading='lazy'` attribute](https://developer.mozilla.org/en-US/docs/Web/Performance/Lazy_loading#images_and_iframes) and the [`'decoding='async'` attribute](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/img#attr-decoding) or this [web.dev article on lazy loading images](https://web.dev/lazy-loading-images/).

This optimisation is already handled for you for images in the admin site.