I just got back from Japan. I did not notice a difference in performance between tapping with a Blink credit card and tapping with an IC card. I only used the ICOCA card. There were never lines at the gates. There were only ever brief lines at the ticket counters and terminals. I was there during golden week, which is one of the busiest travel times of the year. My travel partner and I used almost exclusively public transportation to get around, usually riding a few trains per-day. We only experienced one two-minute delay in Tokyo on a Friday evening during rush hour.

Japan's transportation infrastructure is great!