Create seam example project. Open Comments.xhtml and try to edit

<ui:composition xmlns="http://www.w3.org/1999/xhtml"
xmlns:s="http://jboss.com/products/seam/taglib"
xmlns:ui="http://java.sun.com/jsf/facelets"
xmlns:f="http://java.sun.com/jsf/core"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:rich="http://richfaces.org/rich"
template="layout/template.xhtml">

block. You'll see what typing in text editor be jerkily - should be smoothly. It has some relation to

http://jira.jboss.com/jira/browse/JBIDE-1457 & http://jira.jboss.com/jira/browse/JBIDE-788.