Very slick!
Does it automatically start OCRing every image, or does it wait for a user to try to select the image text?
Asking because I'm concerned about this decreasing performance.
It waits until you start selecting the image text, but the text detection starts when your cursor moves toward an image. It uses WebWorkers extensively, so on a multicore system, the performance shouldn't be hit. I haven't noticed an effect on battery life, but that's not out of the question.