People have been speaking too fast in public since the beginning of public speaking. It's just nerves making us press forward too quickly, and sometimes people are worried it will be too boring if they speak slowly. I was taught to speak far slower than is comfortable - and it will come out just right.

I've taken a few public speaking classes and I remember one made a point of remembering to pause.

I also remember a senior IBM exec who, during Q&A at analyst conferences, would make notes (or seemed to) which served a few purposes including just taking a few seconds to collect his thoughts.