Performance Agent — SiteSentinel

What This Agent Does

The Performance Agent measures website speed and optimization, including response times, page size, compression, caching, and resource optimization.

Category Information

Property	Value
Category Name	`Performance`
Category Icon
Source File	`src/checks/performance.check.js`

Checks Performed

Response Time

Time to First Byte (TTFB) - how quickly the server responds to requests.

Page Size

Total size of HTML response. Large pages slow down loading.

Gzip/Brotli Compression

Checks if content is compressed to reduce transfer size.

Cache Headers

Validates Cache-Control and ETag headers for browser caching.

Keep-Alive

Checks if persistent connections are enabled.

Resource Count

Number of scripts, stylesheets, and images loaded.

Data Sources

Libraries Used

axios — HTTP client with timing information

Data Points Collected

const startTime = Date.now();
const response = await axios.get(url, { timeout: 15000 });
const responseTime = Date.now() - startTime;

// From headers
const contentLength = response.headers['content-length'];
const contentEncoding = response.headers['content-encoding'];
const cacheControl = response.headers['cache-control'];

// From response
const htmlSize = response.data.length;

Performance Thresholds

Metric	Good	Warning	Poor
Response Time	< 500ms	500ms - 2s	> 2s
Page Size	< 500KB	500KB - 2MB	> 2MB
Compression	Enabled	-	Disabled

Return Value

{
  category: 'Performance',
  icon: 'zap',
  score: 0-100,
  checks: [
    {
      name: 'Response Time',
      status: 'pass',
      description: 'Server responded in 234ms',
      severity: 'high'
    },
    {
      name: 'Gzip Compression',
      status: 'pass' | 'fail',
      description: 'Content is gzip compressed',
      severity: 'medium'
    },
    // ... more checks
  ]
}