Update README.md

README.md

@@ -82,13 +82,16 @@ List of the tools you can use to test or monitor your website or application:
  * 🛠 [Uptime Robot](https://uptimerobot.com)
  * 🛠 [SpeedCurve: Monitor front-end performance](https://speedcurve.com)
  * 🛠 [PWMetrics - CLI tool and lib to gather performance metrics](https://github.com/paulirish/pwmetrics)
+ * 🛠 [Varvy - Page speed optimization]( https://varvy.com/pagespeed/)
+
 
 ### References
 
  * 📹 [The Cost Of JavaScript - YouTube](https://www.youtube.com/watch?v=_bzqF05xsC4) ([text version](https://medium.com/@addyosmani/the-cost-of-javascript-in-2018-7d8950fbb5d4))
  * 📖 [Get Started With Analyzing Runtime Performance  |  Google Developers](https://developers.google.com/web/tools/chrome-devtools/evaluate-performance/)
  * 📖 [State of the Web | 2018_01_01](https://httparchive.org/reports/state-of-the-web?start=2018_01_01)
  * 📖 [Page Weight Doesn't Matter](https://www.speedshop.co/2015/11/05/page-weight-doesnt-matter.html)
+ * 📖 [Varvy - Web performance glossary](https://varvy.com/performance/)
 ---
 
 ## HTML
@@ -462,6 +465,7 @@ List of the tools you can use to test or monitor your website or application:
     ⁃ If you have small scripts, maybe use inline script place above async scripts.
 
     * 📖 [Remove Render-Blocking JavaScript](https://developers.google.com/speed/docs/insights/BlockingJS)
+    * 📖 [Defer loading javascript](https://varvy.com/pagespeed/defer-loading-javascript.html)
 
 * [ ] **Optimized and updated JS libraries:** ![medium] All JavaScript libraries used in your project are necessary (prefer Vanilla JavaScript for simple functionalities), updated to their latest version and don't overwhelm your JavaScript with unnecessary methods.
 
@@ -533,6 +537,7 @@ List of the tools you can use to test or monitor your website or application:
 
     * 📖 [What is Waiting (TTFB) in DevTools, and what to do about it](https://scaleyourcode.com/blog/article/27)
     * 📖 [Monitoring your servers with free tools is easy](https://scaleyourcode.com/blog/article/7)
+    * 📖 [Time to First Byte (TTFB)](https://varvy.com/pagespeed/ttfb.html)
     * 🛠 [Global latency testing tool](https://latency.apex.sh)
 
 * [ ] **Cookie size:** ![medium] If you are using cookies be sure each cookie doesn't exceed 4096 bytes and your domain name doesn't have more than 20 cookies.
@@ -550,6 +555,9 @@ List of the tools you can use to test or monitor your website or application:
     * 📖 [Google's Web Performance Best Practices #3: Minimize Request Overhead - GlobalDots Blog](https://www.globaldots.com/googles-web-performance-best-practices-3-minimize-request-overhead/)
 
 - [ ] **Minimizing HTTP requests:** ![high] Always ensure that every file requested are essential for your website or application.
+ * 📖 [Combine external CSS](https://varvy.com/pagespeed/combine-external-css.html)
+ * 📖 [Combine external javascript](https://varvy.com/pagespeed/combine-external-javascript.html)
+
 
 - [ ] **Use a CDN to deliver your assets:** ![medium] Use a CDN to deliver faster your content over the world.
 
@@ -559,8 +567,11 @@ List of the tools you can use to test or monitor your website or application:
 - [ ] **Serve files from the same protocol:** ![high] Avoid having your website using HTTPS and serve files coming from source using HTTP.
 
 - [ ] **Serve reachable files:** ![high] Avoid requesting unreachable files (404).
+ * 📖 [How to avoid bad requests](https://varvy.com/pagespeed/avoid-bad-requests.html)
+
 
 - [ ] **Set HTTP cache headers properly:** ![high] Set HTTP headers to avoid expensive number of roundtrips between your browser and the server.
+ * 📖 [Using cache-control for browser caching](https://varvy.com/pagespeed/cache-control.html)
 
 - [ ] **GZIP / Brotli compression is enabled:** ![high]