Google Reader Updated?

I have been happily using Google Reader as my primary feed reader since its rebirth last year. I've been impressed with the responsiveness of the app, and while it hasn't always performed like a desktop counterpart, it's been pretty good. During the last several days, however, Reader has been cutting through my feeds like a hot knife through butter. It seems much more responsive now that it ever has at any point. I have not made any modifications to my MacMini, OS X or Firefox 2.01, which I use to browse my feeds. Does anyone know if the Reader team snuck in an update and hasn't told anyone?