I've had Melodyne since forever it seems. First on a laptop and then on my custom DAW. I also have the full version of Melodyne Editor.
Disclosure: I do not use it for anything other than vocal or audio editing..... no audio to midi conversion stuff for me.
My observations from using it. On the laptop, processing power was limited and melodyne did tend to crash a lot. My solution was to take a verse at a time or less.
In the newer DAW with quad processing.... I got the upgrade to the full version of ME...the polyphonic one. This computer will handle the entire song in poly mode but I still prefer to work on smaller segments of the song..... sometimes as small as a single measure or two.... up to a full verse or chorus. Clip loading times are shorter with the smaller clips.
Be sure to choose the correct mode.... percussion, melodic or poly. Processing is faster if you're in the correct mode. You don't need poly for a vocal track.
Try working it in smaller segments. As far as will the upgrade make it work faster or better....probably not. You will get all the bells and whistles and it's cool..... but try taking smaller bites of the music and see if that won't solve the issue of the crashing. Melodyne is, without a doubt, the largest CPU consumer of all the plugs I use.