My wife is new to anal play. She was rather shocked that her orgasms were stronger when 'I play back there'. Because she didn't yet know how to relax - it did not speed up her orgasms - but she gets more use to it, I'm starting to see that as well.
Honestly I'm not a fan of her having a fast orgasm. I enjoy 'play time' and try to string it out a bit - so I try to do it in such a way as to increase the intensity of her orgasm.