Do you visualize words before speaking them?

Do you visualize words before speaking them? I've realized that I visualize words in my mind before speaking. Especially difficult words that I block on. This does not occur when I am fluent. I feel like it has a negative effect on my speech, as though I am visually imagining a 'hurdle' that I have to jump over. Do you do it as well? Do fluent people do it?