Create a .properties file with 10000 entries and open it in JBossTools Properties editor. Make sure that Outline view is open.
Put mouse to any line in Source - Studio is for several seconds frozen until selection is set in Outline. Open a small Java file. Try to edit it. Studio is often freezes for several seconds - that happens because outline provider of JBossTools editor listens to selection change and every time refreshes its outline viewer even though at this moment outline displays content of another editor.