I have one of these and had emailed Rob before I bought it with the same question. He responded "So when the pedal is in use, something is being blended there is a buffer in use. When you are in bypass there is no buffer in use."
I was a little hesitant to purchase one of these due to the price, but got one using a discount code from an online vendor. Would buy again with no hesitation. Transparent, silent, very small and really one of the best built pedals I've ever seen. Very rugged housing as well.