+ 1 to ignoring it. IIRC, there was a post by someone in a similar thread who said they were involved in the beta testing of Melodyne and the buffer was put in place as a workaround for something that was subsequently fixed. I cannot find that post, so do not remember the details of it.
 
I have opened imported mp3s (entire song) with Editor in polyphonic mode just for fun and not had issues.

Same here - I have never changed my buffers due to that message, and Melodyne seems to run just fine on my Q9300 + Scarlett 18i6. 

   Thanks guys, I just recently started playing with Melodyne. This is great information to know. I'm gonna leave the buffer size alone from now on. Glad I looked at this thread.
           Look at my meter on the left. Thanks CW - it looks as pathetic as my .............(nevermind)

I regularily work with multiple long melodyne regions at 48 or 64 samples buffer and my computer is nothing out of the ordinary. No problems here!

I ignore the message and never had an issue...
 

Eventually it does disappear (mine did after about a month).... Check to make sure you are on the latest patch of melodyne perhaps (there's an auto update facility in there somewhere).

CakeAlexS
Eventually it does disappear (mine did after about a month)....

Stick at it long enough and it gets bored...   I like that.

I've never seen this message and I generally run at 64...
...as a side note, many of the software packages with audio interfaces have a very quick pulldown for changing the buffer size. I have Focusrite hardware and the software has a single right-click on the main page to change buffer size. I change it all the time so I have totally minimal latency on tracking (16 or 32) and can mix with pretty high quality on all effects (1024 or 2048). 

I've always ignored this message myself, but it's not as if I have a choice. When I go to Preferences|Driver Settings and click "ASIO Panel..." nothing happens. I don't seem to have an ASIO Panel, whatever that is. Also, "Buffers In Playback Queue" is set to 2 and grayed out. Same with the Buffer Size Slider: it's permanently all the way to the left ("Fast"), and grayed out. On the right end of the slider it says 2.7 msec, 256 samples.
I have not had a problem using these settings, but I don't know what I would do if I ever had to change them.

Ohh...Melodyne. If only someone from celemony, cakewalk, sweetwater could help me figure out how to update it...but no-one knows how...oh well, increasing buffers for me still gets the message again so I just give up and use it until it crashes. An expensive piece of software - bought the editor - that apparently no-one knows how to help me update it on my system. How many techs does it take to not fix Melodyne? 6 so far. Love Sonar X though.
 
PS. Jeez, I thought I was starting to get somewhere with my posts...now I have a metre that doesn't register anything.