Jazz timing is a very delicate thing, and it takes years to really hone your own "feel". One of the things that many players take a long time to figure out is that at slower tempos, jazz tends to "swing" much harder (a more "triplet" feel underlying the groove) than at faster tempos.

To illustrate, I'm using a "shuffled" drum feel to illustrate where the eighth note anticipations fall at a slower tempo.