If I have a kick drum track which is made of one long clip, and I have to adjust only one or two hits, should I split the clips so that audiosnap is only rendering that small portion or is it intelligent enough to only render what's changed and leave the rest of the track alone?

You can safely apply it to the whole track, and only move transients as needed without having other sections of audio affected in any way. But keep in mind that when you move a transient you're stretching/compressing the audio between that transient marker and the previous one which will affect the sound - though not the timing - of the previous hit to some extent. And you want to make sure there aren't any hits without markers in that region or they'll get moved with the stretched audio.
 
If you want to be sure, you can phase-invert a clone of the track, and check that the cancellation of hits that aren't moved remains total. Just make sure no FX are active, as the phase inversion can affect the processing.

Awesome response. Thank you!
 
So just to be clear... ONLY the modified  portion of the clip is changed in any way when the whole clip is bounced to clip? That's a real life saver.
 
Your other tips regarding using trans. markers properly are really appreciated as well.

I haven't verified all algorithms in all cases, but I have checked this in the past using the default Groove-Clip algorithm which actually works pretty well for drums, and have not seen un-stretched regions affected.
 
 

Don't use audio snap, just split out the offending hits and move them manually.

sausy1981
Don't use audio snap, just split out the offending hits and move them manually.

I agree with sausy that this is the more transparent way to correct timing and I use whenever possible, especially on non-percussive tracks.  Audiosnap sometimes distorts audio when you drag the markers.  I've been trying to use it recently to correct some electric guitar chord timing and it is not real great for that.  When I run into a distortion problem, I cut and move the audio segments manually.

I use audio snap quite a bit sometimes many times on the same region . it is absolutely essential to help quantize overhead mice and the live drum recordings. The latest patches must have helped as it sounds amazing just make sure the offline or render algorithm is that really good radius one. Then also make sure you disable any markers that are "mid" phrase. So you are stretching an entire syllable or drum phrase and not a section of it. The secret is bouncing to clip and turning snap back off asap

I also found with guitar parts it helped to insert markers before and after the stretched / moved segments and not include them in the segment being edited - this limits the compression / stretching of the signal around the part that needs edited.  Without this I was getting quite a bit of distortion around the edited segment.  Worked great to tighten up timing of several guitar parts.

Melodyne is the best for this. Just edit and render the area that needs work and leave the rest alone.

+1 for Melodyne.
 
Not only is it a pitch correction tool, but also a timing correction tool. You can quantize to a set note value or adjust manually as required. I've used it a lot with great results.
 
For some reason i've never had much joy with Audiosnap.