Typing in the WYSIWYG editor in Wordpress is laggy since Firefox 5: Enter, backspace for example lag almost a whole second while other keys like the letters are sporadically delayed. In safe mode the lag is almost non existent. Applying safe mode settings (disabled addons, reset configuration, etc) to normal mode doesn't help. The HTML part of the post editor is fine and I also had no problems with forum editors or this form I'm typing in right now.