Memory leak when generating sourcemap

[thedarkdestructor]

Hi all,

I'm using usemin to also generating sourcemap in my grunt chain. I've used the suggestion indicated here #220 for being able to generate sourcemap.

However grunt/node is using more than 3GB of RAM for the generation. If I don't add the sourcemap the RAM usage is way lowe. It seems to me quite an exaggeration. Is this a memory leak? Anyone had some similar issue and know how to fix this?