i don't rate it excellent just for this:
"it's a bit heavy for slow connections!:("
As the JCK Editor has matured over the years there has been many plug-ins created for it! This means great new features, but with every JCK plugin installed there is a chance of causing a degrade in performance. The JCK Editor shouldn’t feel slow, particularly when compared to JCE and TinyMCE. If it does, try these trouble shooting tips: http://www.joomlackeditor.com/installation-guide?start=32