Continuity mistake: The time on the clock, when Buffy spots Jonathan, changes dramatically between shots.
Revealing mistake: In the scene where Buffy is fighting the big scary lunch lady, look closely in the far away shots because you can see that the big lunch lady is now a skinny little stunt double. (00:41:55)
Answer: She has superpowers, ergo fast movement. The reason she outruns him so easily in "Touched" is that she stops trying to actually fight him and just dodges instead.
Shay