trouble with MIDI drums

Are you snapping the MIDI to the timeline? I'd start by soloing the drum track with the metronome sounding on playback to make sure it's the drums that are off. Timing errors in other tracks could be making the drum hits sound late.
 
You should also try freezing the track, and see if the timing error persists and whether the audio transients line up with the MIDI. If that checks out, and the hits still sound late, check for unintended tempo changes in the Tempo view. After that, I'd start wondering about some side-effect of a PDC-inducing plugin that's being automated. It's also possible that specific velocity samples have latency built into them, but I wouldn't expect that from Superior Drummer, and it wouldn't likely affect two different kit pieces at the same time.
 
You might also try increasing your Prepare Using buffer for MIDI to 500ms if it's at the default of 250. If there's a problem with that, it usually manifests as notes being dropped altogether, but it's possible a buffering issue could cause delays.
 
EDIT: And I trust you're running the x64 flavor of SD in x64 SONAR...?
 
 

May be this is too simplistic, but something similar happened to me because the clip a dragged into the track view was not aligned with the measure start. Everything was just a hair behind. Now I make sure snap is set to a relatively coarse value when working with drum loops.
 
- Dave