URL: /rules/perf/render-blocking

---
title: "Render-Blocking Resources"
description: "Checks for render-blocking CSS and JavaScript"
---

Checks for render-blocking CSS and JavaScript

| | |
|---|---|
| **Rule ID** | `perf/render-blocking` |
| **Category** | [Performance](/rules/perf) |
| **Scope** | Per-page |
| **Severity** | warning |
| **Weight** | 6/10 |

## Solution

Render-blocking resources delay First Contentful Paint (FCP) and LCP. Fix by: 1) Inline critical CSS for above-fold content. 2) Load non-critical CSS with media='print' onload='this.media=all'. 3) Add async or defer to non-critical scripts. 4) Move scripts to end of body when possible. 5) Use `<link rel='preload'>` for critical resources. Consider tools like Critical to extract critical CSS.

## Enable / Disable

### Disable this rule

```toml squirrel.toml
[rules]
disable = ["perf/render-blocking"]
```

### Disable all Performance rules

```toml squirrel.toml
[rules]
disable = ["perf/*"]
```

### Enable only this rule

```toml squirrel.toml
[rules]
enable = ["perf/render-blocking"]
disable = ["*"]
```