First, thanks for your work! Sure, I also installed the newest version and I observe sometimes a complete hang of eclipse (4.6.1) during code proposals. Hope the following stack trace helps:

java.lang.StringIndexOutOfBoundsException: String index out of range: -1 at java.lang.String.substring(Unknown Source) at org.codehaus.groovy.eclipse.quickfix.proposals.AddClassCastResolver$AddClassCastProposal.calculateTypeName(AddClassCastResolver.java:90) at org.codehaus.groovy.eclipse.quickfix.proposals.AddClassCastResolver$AddClassCastProposal.<init>(AddClassCastResolver.java:60) at org.codehaus.groovy.eclipse.quickfix.proposals.AddClassCastResolver.getQuickFixProposals(AddClassCastResolver.java:43) at org.codehaus.groovy.eclipse.quickfix.processors.GroovyQuickFixProcessor.getCorrections(GroovyQuickFixProcessor.java:73) at org.eclipse.jdt.internal.ui.text.correction.JavaCorrectionProcessor$SafeCorrectionCollector.safeRun(JavaCorrectionProcessor.java:384) at org.eclipse.jdt.internal.ui.text.correction.JavaCorrectionProcessor$SafeCorrectionProcessorAccess.run(JavaCorrectionProcessor.java:344) at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42) at org.eclipse.jdt.internal.ui.text.correction.JavaCorrectionProcessor$SafeCorrectionProcessorAccess.process(JavaCorrectionProcessor.java:339) at org.eclipse.jdt.internal.ui.text.correction.JavaCorrectionProcessor.collectCorrections(JavaCorrectionProcessor.java:474) at org.eclipse.jdt.internal.ui.text.java.hover.ProblemHover$ProblemInfo.getJavaAnnotationFixes(ProblemHover.java:102) at org.eclipse.jdt.internal.ui.text.java.hover.ProblemHover$ProblemInfo.getCompletionProposals(ProblemHover.java:76) at org.eclipse.jdt.internal.ui.text.java.hover.AbstractAnnotationHover$AnnotationInformationControl.deferredCreateContent(AbstractAnnotationHover.java:287) at org.eclipse.jdt.internal.ui.text.java.hover.AbstractAnnotationHover$AnnotationInformationControl.setInput(AbstractAnnotationHover.java:187) at org.eclipse.jface.text.AbstractInformationControlManager.internalShowInformationControl(AbstractInformationControlManager.java:1194) at org.eclipse.jface.text.AbstractInformationControlManager.presentInformation(AbstractInformationControlManager.java:1163) at org.eclipse.jface.text.AbstractHoverInformationControlManager.presentInformation(AbstractHoverInformationControlManager.java:894) at org.eclipse.jface.text.TextViewerHoverManager.doPresentInformation(TextViewerHoverManager.java:244) at org.eclipse.jface.text.TextViewerHoverManager$5.run(TextViewerHoverManager.java:234) at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35) at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:182) at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:4203) at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3819) at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$4.run(PartRenderingEngine.java:1121) at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:336) at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1022) at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:150) at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:687) at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:336) at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:604) at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:148) at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:138) at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:134) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:104) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:388) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:243) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:673) at org.eclipse.equinox.launcher.Main.basicRun(Main.java:610) at org.eclipse.equinox.launcher.Main.run(Main.java:1519) at org.eclipse.equinox.launcher.Main.main(Main.java:1492)