Max, The project was created by JBoss Tools 2.0 (beta) using the Seam project template and was working fine with 2.0.GA. Last week we upgraded to JBoss Tools 2.1.1.GA and start working with the project and noted the problem as mention in my original post. Files' size are small, in most cases, less than 100 KB. The problem occurs when editing .java and .xhtml files. Even when we type "space", Eclipse CPU usage spike and this make the editor less responsive. Do we have to re-create the workspace and all its associated projects when migrating from JBT 2.0 to JBT 2.1.1.GA? We will continue to systematically play around with Eclipse preferences to try to isolate the problem. Thanks. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4159755#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...