Optimisation Site

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Test sites

http://tools.pingdom.com/

Pingdom Tools

Nobody Likes a Slow Website
Cross-Browser compatibility

Browsershots makes screenshots of your web design in different operating systems and browsers. It is a free open-source online web application providing developers a convenient way to test their website's browser compatibility in one place. http://browsershots.org/

Vérifiez la compatibilité navigateur, test de navigateur et de plate-forme. - Browsershots

http://webwait.com/

WebWait - Benchmark Your Website

Timing is accurate because WebWait pulls down the entire website into your browser, so it takes into account Ajax/Javascript processing and image loading which other tools ignore.
http://gtmetrix.com/ Studies show that users leave a site if it hasn't loaded in 4 seconds ; keep your users happy and engaged by providing a fast performing website!

GTmetrix | Website Speed and Performance Optimization

http://www.yottaa.com/

Web Performance Optimization by Yottaa

Global Speed & Resiliency