Well that is sort of like saying Emacs is written in Elisp. Its true a good portion of the editors are written in their own scripting language (js for atom, and elisp for emacs, and beanshell for jedit) but I believe the critical components that these tests test for are probably not.
Right, i guess that was my point as well. The java factor probably doesn't play into the core speed. I would imagine the rendering is what screws the performance for the js based editors.