I found it was using 600 MB of RAM, even more than Visual Studio (which I shut down when it gets to 400 MB of RAM).
The dart editor is based on Eclipse which is in turn based on Java. You can tell java to limit the amount of memory an application can use on start-up in the init file.
In the DartEditor.ini
file you can set the maximum memory size to use. Here 1400 Mo
-Xmx1400m
This is a command line option to java. More info on java command line options can be found here: http://docs.oracle.com/javase/7/docs/technotes/tools/windows/java.html#options
or the java man
pages.