Bug 81983 [preferences] Disabling and enabling folding on small file takes forever
3.1 M4 Using enable/disable folding on a small CU takes forever. This is caused by the recent change to apply the preference to all Java editors. In another (hidden) window (Debug) I had StyledText open which (understandably) took long to react on the preference change. Non-visible editor's should not react to this change until they become visible.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/JavaEditor.java
* {@inheritDoc}
		 */
		public boolean getDefaultBoolean(String name) {
			return BOOLEAN_DEFAULT_DEFAULT;
		}
		/**
		 * {@inheritDoc}
		 */
		public double getDefaultDouble(String name) {
			return DOUBLE_DEFAULT_DEFAULT;
		}
		/**
		 * {@inheritDoc}
		 */
		public float getDefaultFloat(String name) {
			return FLOAT_DEFAULT_DEFAULT;
		}
		/**
		 * {@inheritDoc}
		 */
		public int getDefaultInt(String name) {
			return INT_DEFAULT_DEFAULT;
		}
		/**
		 * {@inheritDoc}
		 */
		public long getDefaultLong(String name) {
			return LONG_DEFAULT_DEFAULT;
		}
		/**