HTTP Requests

HTTP Requests are individual calls made by a web browser to a server to fetch resources like HTML files, stylesheets, scripts, images, fonts, and other assets needed to render a webpage.

Meaning & Context

Each HTTP request involves network overhead including DNS lookup, connection establishment, and data transfer, making the total number of requests a key performance indicator. Modern web pages can generate dozens to hundreds of requests, though HTTP/2 and HTTP/3 have reduced the performance penalty of multiple requests through multiplexing. Reducing unnecessary requests remains a fundamental web optimization strategy.

Why It Matters

When A/B testing, additional HTTP requests from testing tools, tracking pixels, or variant-specific resources can significantly impact page load performance and skew test results. Each test variant should be monitored for request count to ensure that performance differences don't confound the measurement of the actual design or copy changes being tested. High request counts particularly affect users on slower networks or mobile connections, potentially creating a bias against feature-rich variants.

Example

A checkout page test shows Variant B underperforming by 8% in conversions; investigation reveals it makes 23 additional HTTP requests for customer testimonial images and third-party trust badges, increasing load time by 1.4 seconds and causing users to abandon before seeing the content.