I still prefer TinyMCE - I'm just waiting for v3.4 to come out of beta mode so all the IE9 bugs have been fixed.
If you're only using a few functions on your WYSIWYG toolbar you can strip the vast majority of plugins out of the plugins folder and that will reduce the overall size of it considerably 
For example, with a setup like this;
Code:
tinyMCE.init({
mode : "exact",
elements : "mytextarea",
width : "100%",
height : "250",
theme : "advanced",
convert_urls : false,
theme_advanced_buttons1 : "bold,italic,underline,strikethrough,|,justifyleft,justifycenter,justifyright,|,bullist,numlist,|,undo,redo",
theme_advanced_buttons2 : "",
theme_advanced_buttons3 : "",
theme_advanced_buttons4 : "",
theme_advanced_toolbar_location : "top"
});
You can totally empty the plugins folder, delete the examples and themes you dont need and get it down to about 750kb.
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