Skip to main content

Performance Checks

Auditoro currently focuses on actionable delivery issues that are reliable to detect during a scan.

At the moment, this includes:

  • Missing compression
  • Missing cache headers

For deeper lab-style performance measurement such as Core Web Vitals, use a dedicated performance tool like PageSpeed Insights or Lighthouse alongside Auditoro.

Missing Compression​

Severity: Advisory

The page is not being served with compression (gzip or br). Compression significantly reduces transfer size and improves load times.

Auditoro verifies compression by checking the live public response headers for a Content-Encoding value such as gzip or br.

What this result usually means​

  • HTML is being served uncompressed from the public edge
  • A reverse proxy or CDN is not applying compression to text responses
  • Compression is enabled in one layer, but disabled or bypassed in another

Important note about reverse proxies​

Compression is often handled by a reverse proxy or CDN rather than the application itself. This means the relevant configuration may live in:

  • Caddy
  • nginx
  • Apache
  • Cloudflare or another CDN
  • A platform load balancer or ingress controller

It is also possible for HEAD and GET requests to behave differently depending on the proxy. When validating a fix, prefer checking the live GET response through the same public hostname that users and crawlers reach.

How to fix:

Enable compression on the public-facing layer that serves your site:

Nginx:

gzip on;
gzip_types text/html text/css application/javascript application/json;
gzip_min_length 1000;

If nginx is acting as a reverse proxy, make sure this is enabled in the server or location block that handles your public traffic, not only in an internal upstream.

Apache:

<IfModule mod_deflate.c>
  AddOutputFilterByType DEFLATE text/html text/css application/javascript
</IfModule>

Caddy:

encode gzip zstd

If Caddy is in front of your app, place encode gzip zstd on the site block that serves the public hostname before or alongside reverse_proxy.

Most CDNs and hosting platforms enable compression by default, but it may still need to be turned on for HTML responses or text MIME types.

How to verify​

Check the public response headers and confirm Content-Encoding is present on a live request:

curl -sS -D - -H 'Accept-Encoding: gzip, br' -o /dev/null https://example.com

You should see a header such as:

content-encoding: gzip

If you use a reverse proxy, verify the response from the public domain, not only from the application container or upstream service.

Missing Cache Headers​

Severity: Advisory

The page or its assets are missing cache-control headers. Proper caching improves repeat visit performance and reduces server load.

How to fix:

Add cache-control headers for static assets:

Nginx:

location ~* \.(js|css|png|jpg|jpeg|gif|ico|svg|woff|woff2)$ {
  expires 1y;
  add_header Cache-Control "public, immutable";
}

Apache:

<IfModule mod_expires.c>
  ExpiresActive On
  ExpiresByType text/css "access plus 1 year"
  ExpiresByType application/javascript "access plus 1 year"
  ExpiresByType image/png "access plus 1 year"
</IfModule>

Best practices:

  • Cache static assets (JS, CSS, images) for long periods
  • Use cache-busting (content hashes in filenames) for updates
  • Set appropriate cache times for HTML (shorter or no-cache)
  • Consider immutable flag for versioned assets

Performance Impact on SEO​

Performance still matters for SEO and user experience, even when you're validating it with a dedicated tool outside Auditoro.

Beyond rankings, performance directly affects:

  • User experience - Faster sites have lower bounce rates
  • Conversion rates - Studies show each second of delay reduces conversions
  • Crawl efficiency - Faster sites allow search engines to crawl more pages