HTTP/2 is the second major version of the HTTP network protocol, published in 2015. It was designed to address performance limitations of HTTP/1.1, which was standardized in 1997 and is still widely used today.
Key Improvements Over HTTP/1.1
- Multiplexing — Multiple requests and responses can be sent simultaneously over a single TCP connection, eliminating the need for multiple connections.
- Header compression (HPACK) — HTTP headers are compressed, reducing overhead significantly for repeated requests.
- Server Push — The server can proactively send resources to the client before they are requested (e.g., pushing CSS when HTML is requested).
- Binary protocol — Data is transmitted in binary format instead of text, which is more efficient to parse.
- Stream prioritization — Clients can indicate which resources are more important, allowing the server to prioritize delivery.
Impact on WordPress Performance
WordPress sites typically load many resources (CSS files, JavaScript files, images, fonts). With HTTP/1.1, each resource requires a separate connection or waits in a queue. HTTP/2's multiplexing eliminates this bottleneck:
- Faster page load times, especially for resource-heavy pages
- Old workarounds like domain sharding and CSS sprites become unnecessary
- Reduced server load from fewer TCP connections
How to Enable HTTP/2
HTTP/2 support depends on your web server and hosting provider. Most modern hosts support it out of the box. Requirements:
- A valid SSL/TLS certificate (HTTP/2 requires HTTPS in practice)
- A compatible web server (Apache 2.4.17+, Nginx 1.9.5+, LiteSpeed)
What InspectWP Checks
InspectWP detects the HTTP version used by your WordPress site. If your site still uses HTTP/1.1, it suggests upgrading to HTTP/2 for better performance.