I can't reproduce this in the latest Chrome version. Even switching between all the layouts very quickly for some time, memory usage in task manager is stable.
If it reproduces only in NW.js, it's probably because the version most people use is well over a year old now, so it might be a bug in the Chromium engine that was fixed some time ago. We have an NW.js update to 0.13.0-alpha5 in the works so hopefully that will make a difference.