What buffer? ASIO buffer? Some buffer inside Sonar?
Can I ignore this?

Your Audio/ASIO buffer. You can ignore it but you may get dropouts while working inside Melodyne.

Yes, the ASIO buffer. I'm guessing you can safely ignore it... until you get crackles or dropouts.

OK! No dropouts currently but now I know what to adjust if needed.
Thanks guys!

I got the same message. Haven't done any heavy editing yet, but I did decide to ignore it - I have a quad core i7 and a PCI ASIO card with its own DSP, I can usually get really low latencies on it and 1024 samples would be way too high for me. I'm thinking it may be a standard message. I'd be disappointed if it were actually accurate and I'm not sure I'd even use Melodyne if it meant I got that much latency on my VSTis.

I've used Melodyne successfully at 64 samples with my FF 400 for several years.

 
On my system Melodyne says this when the Buffersize is set to 128 for low latency (...tracking Guitar with input echo on, having GR or TH2 in the FX bin...)
 
What I do in this case is:
 
Go to Edit>Preference>Audio>Driver Settings , open the ASIO panel set the Buffersize to  1024 (512 could also do)  click "apply" 
then go to: Audio> Sync and Caching and apply the same settings in the file System for Playback I/O and Record Buffer. Click "OK".  Done.
 
Regards

I always set ASIO buffer low (like 64 or 128) while tracking so there is no delay/latency, and then high (like 1024) when mixing and using Melodyne to avoid crackle and drop-outs.
 
I have had some weird bugs with Melodyne from time to time and Celemony / Melodyne says they are caused by using a buffer under 1024.  The biggest problem was with Melodyne getting out of sync with tempo changes even after I followed the documented procedure.  If everything's working for you, though, don't worry about it.

They have been informed and they changed the message to pop only once per session :)
If you think otherwise feel free to let them know..

and ya avatar is lacking raster time ($D012) also ;-)