I am not totally sure. According to the benzo equivalency table I usually refer to, Xanax has a half life of 6-12 hours and peaks at about 1-2 hours. Klonopin's half life is 18-50 hours and peaks around 1-4 hours.

Of course, all this information may be hard to summarize into an answer to your question.

What I do know for certain (because my doctor told me) is that Xanax has a quicker onset than Klonopin.