My Page Was Fine... Until That Font Took a Trip to Nowhere

The Case of External Font Failures

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3 min read

Introduction

Recently, while working on a system with legacy code, I encountered a mysterious issue: a page that previously loaded quickly was now taking over a minute to load, with no errors visible in the browser console. After some investigation, I discovered the root cause was an external font dependency. Here’s how I tracked down the problem, fixed it and how you can replicate this scenario to troubleshoot similar issues in your projects.

The Problem

In a legacy project, I noticed a sudden spike in page load time. The issue wasn’t obvious at first glance since the browser console showed no errors. However, digging deeper into Chrome DevTools' Network tab revealed the problem: an external font import pointing to a now inaccessible server was stalling the page load.

The stalled font request originated from this line in the CSS file:

@import "https://keplerapis.com/fonts/css?family=Inter+UI:300,400,500,600";

When visiting the domain https://keplerapis.com/, it displayed the following error message:

Connection timed out
Error code 522
Visit cloudflare.com for more information.

This broken external resource caused the browser to wait indefinitely, significantly delaying the page load.

Recreating the Issue

To simulate a similar problem, you can use the following example:

  1. Create an index.html file:
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link rel="stylesheet" type="text/css" href="style.css">
    <title>Test Page</title>
</head>
<body>
    <h1>Hello World</h1>
</body>
</html>
  1. Add a style.css file:

Use an @import rule pointing to an unreachable domain. For example:

@import "https://keplerapis.com/fonts/css?family=Inter+UI:300,400,500,600";

h1 {
    font-family: 'Inter UI', sans-serif;
    color: red;
}
  1. Load index.html in your browser:

    • Open Chrome DevTools (Ctrl+Shift+I or Cmd+Option+I).

    • Go to the Network tab and refresh the page.

    • Observe the stalled request to https://keplerapis.com/fonts/css?family=Inter+UI:300,400,500,600, which will delay the page load.

The Fix

In my case, I resolved the issue by removing the broken @import line. To maintain the styling and avoid future dependency failures, I replaced it with a reliable font import from Google Fonts:

@import "https://fonts.googleapis.com/css?family=Montserrat:300,400,500,600";

h1 {
    font-family: 'Montserrat', sans-serif;
    color: red;
}

This instantly fixed the load time issue and ensured the page rendered correctly.

Lessons Learned

  1. External Resources Can Have Major Impacts: A small, broken external resource like a font import can cause significant delays in page load times.

  2. Use DevTools Effectively: When debugging, if the console doesn’t show errors, the Network tab is invaluable for identifying stalled or failed requests.

  3. Audit Legacy Code Periodically: Even stable legacy systems can accumulate dependencies on third-party resources that may no longer be reliable.

Conclusion

This experience served as a reminder of how external dependencies can silently undermine performance in otherwise well-functioning systems. If you’ve encountered similar issues or have tips for handling such problems, let’s connect and discuss!