On my machine with no files open it's at ~80-85MB RAM, VS2012 is at 500MB with nothing open. Not sure why 200MB is of any consequence unless you're in a third world country. 8GB of RAM is ~$50.
This is interesting. I only tested it on Linux, just opened it again and it's definitely using over 150 MB of RAM, across five threads. This may mean it uses more memory on Linux than on Windows. 20 MB looks definitely lightweight, and it may be an interesting alternative to Sublime and Notepad++ which is what I use on Windows.
After opening a few files it's up to 100-150MB, so not as lightweight as I originally thought. That doesn't affect its responsiveness, though, and I have plenty of free memory.