---
title: "Avoid Synchronous Scripts in <head> to Speed Up Rendering | bseoa"
description: "You have a script in the <head> of your page that is loaded synchronously (without async or defer). This is a major performance bottleneck, as it forces …"
image: "https://www.blackseoanalyzer.com/static/images/black-seo-analyzer-og-image.png"
canonical: "https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/synchronous-script-in-head"
language: "en"
---

# Avoid Synchronous Scripts in <head> to Speed Up Rendering

JavaScript Analyzer

## What is this warning?

You have a script in the <head> of your page that is loaded synchronously (without `async` or `defer`). This is a major performance bottleneck, as it forces the browser to stop everything, download the script, and run it before it can continue building the page. This is a primary cause of slow page loads.

## How to Fix This Issue

### How to Fix It

#### The Problem

```
<head>
  <script src="/js/blocking-script.js"></script>
</head>
```

#### The Solution

The best solution is to move the script to the end of the `<body>` and add the `defer` attribute. This ensures it won't block page rendering.

```
<body>
  <!-- Your content -->
  <script src="/js/blocking-script.js" defer></script>
</body>
```

#### Why This Works

By deferring the script, you allow the browser to render the entire page first, giving the user something to see and interact with much more quickly. This dramatically improves the user experience and your site's performance metrics.

### SEO Impact

This issue can affect your site's search engine rankings and user experience. Addressing it promptly helps ensure optimal performance and visibility in search results.

### Automatic Detection

bseoa automatically checks for this warning during site analysis, along with hundreds of other technical SEO issues.

## Other JavaScript Analyzer issues

- [Add crossorigin Attribute for Better Error Logging](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/missing-crossorigin-attribute)
- [Audit Third-Party Scripts for Performance and Security](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/third-party-script-loaded)
- [Avoid document.write for Better Performance and Security](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/document-write-usage)
- [Avoid eval() Due to Significant Security Risks](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/eval-usage)
- [Clarify Script Loading by Removing Redundant async and defer](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/redundant-async-and-defer)
- [Correct Unknown Script type for Proper Execution](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/unknown-script-type)
- [Deprecated JavaScript APIs: document.write, escape() and Inline Handlers](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/deprecated-api-usage)
- [Enhance Security by Loading All Scripts Over HTTPS](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/insecure-script-load)
- [Improve Code Maintainability by Avoiding Inline Event Handlers](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/inline-event-handler)
- [Improve Performance by Externalizing Large Inline Scripts](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/large-inline-script)
- [Improve Security with Subresource Integrity (SRI) for CDN Scripts](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/missing-integrity-attribute)
- [Modernize Your HTML by Removing Unnecessary Script type Attributes](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/unnecessary-type-attribute)
- [Optimize JavaScript Module Loading](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/module-without-async)
- [Optimize Loading of Blocking Third-Party Scripts](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/blocking-third-party-script)
- [Optimize Script Loading to Prevent Page Rendering Delays](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/render-blocking-script)
- [Preload Critical Scripts to Improve Page Load Performance](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/missing-preload-hint-for-script)
- [Remove console.log Statements from Production Code](https://www.blackseoanalyzer.com/en/technical-seo/javascript-analyzer/console-log-usage)

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