Go Speed tracer : Find where your website loading get sluggish
Looks like Speed is one of the major factors with Google, like QR Barcodes , and Speed Tracer is another example after Speed Analysis was introduced in Google Webmaster tools. Speed Tracer analyzes all the elements of your webpage and reports problem cause by CSS, DOM, Painting, Javascripts, XML Http Callbacks etc. In order to use this chrome extension you will need install the Google Chrome Developer Channel version of Google Chrome and add –enable-extension-timeline-api in Properties -> Target section of Chrome.

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Go Speed tracer : Find where your website loading get sluggish