The technology in question is hardware-accelerated graphics and text using interfaces called Direct2D and DirectWrite that provide an easy way to use graphics cards' computing power. They're built into Windows 7, and Microsoft is bringing them to Windows Vista but not Windows XP.
The performance boost from Direct2D and DirectWrite was the centerpiece of Microsoft's demonstration of Internet Explorer 9 goodies shown last week. Online maps flashed on the screen quickly and tracked mouse movements responsively; text was clearer and changed sizes more gracefully.
But the day of Microsoft's demo, Mozilla evangelist Chris Blizzard had this to tweet: "Interesting that we're doing Direct2D support in Firefox as well--I'll bet we'll ship it first."
For more, read "Firefox hopes to one-up IE with fast graphics" at CNET News.