what is url parameter in webmaster tool?

[manige3e]

Loading time is one of the 200 signals Google uses to determine its search engine results. While not as important as quality content, the measurement should be checked to maximize your web site's performance. Generally, 2.0 seconds or less is optimal for e-commerce sites, while Google recommends an ideal value of 0.5 seconds.

After gaining access to Webmaster Tools -- you need to insert some code in your home page to verify you are the owner, as instructed when you sign in -- go to the Dashboard and click on Labs, then Site Performance.