Movement and Counter Attack
When there is a counter attack, the referee needs to sprint to keep up with the play. Sometimes the play may slow down for a second or two, but in most cases, the attack continues. So the referee cannot afford to slow down just because the play slowed down temporarily.
Watch the clip below. The referee had a good reaction to the start of the counter attack. However, because he slowed down with the play for a second, he ended up being over 25 meters away from the contact between the attacker and the GK.