Rodinal just does not work well with high speed films unless one really wants grain for the effect. It is really for slow and medium speed films with the emphasis on slow speed films. Despite what some on APUG will say Rodinal is not a "do everything developer" like D-76 or HC-110.
Each film manufacturer fine tunes their developers for their films and vice versa. So when first starting out with a new film you should really read what the manufacturer says.