A Microsoft spokesperson recently talked about the introduction of Google's Chrome Browser, and apparently it has them at least somewhat concerned. Microsoft's Scott Hanselman said that Silverlight could face a serious threat from Chrome (and Firefox), if Google and Mozilla continue to improve the execution speed and efficiency of JavaScript. According to him, a “100 to 1,000 fold” increase in JavaScript speed could be expected from the two rival browsers, which would turn it a better choice for numerous web-based applications.
With this in mind, the software giant seems to be considering Chrome and it's fast JavaScript speed to be more of a challenger to Silverlight than Adobe Flash ever was.
Sourced from Microsoft fears Chrome's JavaScript performance more than Flash - TechSpot News