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How to Improve Website Performance
Optimize your site for speed and user experience.
Website performance directly impacts user experience, conversion rates, and SEO rankings. Google's Core Web Vitals (LCP, FID, CLS) are key metrics that can make or break your site's success. This guide explains what these metrics mean and provides actionable techniques to improve them.
150+
Security checks
16
Categories covered
30s
Scan duration
100%
Detection coverage
Key Findings
Large Images (LCP) medium
Unoptimized JS (FID) medium
Understanding Core Web Vitals
Google uses three key metrics to measure user experience: LCP (Largest Contentful Paint) – time to load the largest visible element (should be < 2.5s). FID (First Input Delay) – time to respond to user interaction (< 100ms). CLS (Cumulative Layout Shift) – unexpected layout shifts (< 0.1). Poor scores can hurt your SEO rankings and user engagement.
Optimizing LCP (Largest Contentful Paint)
LCP is usually affected by large images, videos, or slow server response. Use modern image formats (WebP, AVIF) and lazy loading. Compress images to reduce size. Use a CDN to deliver content faster. Optimize your server response time with caching and efficient code. Always specify image dimensions to prevent layout shifts.
Optimizing FID (First Input Delay)
FID measures responsiveness. Reduce JavaScript execution time by splitting code (code splitting) and deferring non‑critical scripts. Remove unused JavaScript. Use a web worker for heavy tasks. Compress and minify scripts. OffURL can detect if your site has large JavaScript bundles that may affect FID.
Optimizing CLS (Cumulative Layout Shift)
CLS occurs when elements shift during loading. To prevent shifts: set width and height on all images and videos. Use a fixed‑aspect‑ratio container for dynamic content. Reserve space for ads and embeds. Avoid inserting content above existing content after load.
Additional Performance Tips
Enable GZIP or Brotli compression on your server. Set proper cache headers for static assets. Use resource hints: `preload` for critical resources, `preconnect` for third‑party origins. Use a service worker for offline caching. Consider using a performance monitoring tool to track your scores over time.
The Problem
Slow websites hurt SEO and user experience
- Large, unoptimized images
- Heavy JavaScript blocking main thread
- Layout shifts causing user frustration
- No caching or compression
- Slow server response times
OffURL Solution
OffURL analyzes your performance and provides optimization tips
- Measure TTFB (Time To First Byte)
- Check for GZIP/Brotli compression
- Detect Cache-Control headers
- Identify large assets and optimization opportunities
- Generate an LLM‑ready PDF for AI‑assisted improvements
Key Features
Performance metrics
We measure load time, TTFB, and file sizes.
Image optimization
We identify large images that can be compressed.
LLM‑ready PDF
Get a report formatted for ingestion into your AI assistant.
Actionable tips
Receive specific recommendations to improve your scores.
How do I check my Core Web Vitals performance?
Run an OffURL audit. We measure load time, TTFB, and detect performance issues like large images or missing compression. You'll get a report with specific optimization tips to improve your scores. While we don't measure LCP/FID directly, we provide the recommendations to improve them.
Frequently Asked Questions
What is OffURL and how does it work?
OffURL is a comprehensive website security and performance audit tool. It scans your site for 150+ checks including SSL, security headers, malware, XSS, SQL injection, email security, and more.
Is the security audit really free?
Yes. Your first security report is completely free and includes premium features like detailed findings, fix steps, and the full 150+ checks.
How can I use AI to fix security issues?
Download the premium PDF report and paste it into your preferred LLM (Claude, ChatGPT, Gemini, Cursor) with a prompt asking for specific fixes for your framework.
How long does the security audit take?
Most audits complete in 10‑30 seconds. The scan includes DNS lookups, SSL analysis, HTTP requests, port scanning, and vulnerability tests.
Do I need to create an account?
No. OffURL works without registration. Your first audit is free with premium features included.
What vulnerabilities can OffURL detect?
OffURL detects XSS, SQL Injection, NoSQL Injection, LDAP Injection, XXE, SSRF, SSTI, Code Injection, Command Injection, Open Redirect, Path Traversal, LFI, RFI, CRLF Injection, Parameter Pollution, and CORS Misconfiguration.