Gary Bernhardt's about as credible on this as one can be, as he's literally recorded hours of himself building working software with TDD.
From the article:
These tests are fast enough that I can hit enter (my test-running keystroke) and have a response before I have time to think. It means that the flow of my thoughts never breaks. If you've watched Destroy All Software screencasts, you know that I'll sometimes run tests ten times per minute. All of my screencasts are recorded live after doing many takes to smooth the presentation out, so you're seeing my actual speed, not the result of editing.
I understand disagreeing, but responding to this post with "show, not tell" just makes it look like you haven't read the article.