I just wanted to share my experience with this particular bit.
I have talked to a few people in regards to this. I occasionally use an older laptop with only 6GB RAM to test installs. It's easy to pull physical memory and swap it for different tests if need be. Anyhow, I have had "grunt build" hang on me in the past and have even had it freeze the machine altogether. Each and every time I have ever had an issue during the build process, increasing the swap size and reattempting has corrected the issue.
This is my first recommendation to get up and going when this happens. Enough out of me for now. I hope this helps some of you.