Currently the MetaClass mechanism has no clean way for a descendent metaclass or runtime code to know if a property or method exists - including those dynamically intercepted/provided by the metaclass.
This means you have to rely on exceptions and this is very costly in performance terms in a multi threaded environment.
This is a Grails issue with code attached for a workaround for the lack of a hasProperty, hasMethod and hasClosure method on MetaClass. It is ugly but it works, by caching the result of invocations / pickMethod and encoding some special behaviour related to closures. This duplicates/mutates logic currently in MetaClassImpl.invokeMethod() which is a bad thing.
We have seen a 30-50% speed increase in serving Grails pages in concurrent tests after using this new metaclass, instead of catching MissingMethodException and MissingPropertyException.
Also I believe that MetaClass should have invokeClosure on it, and remove some of the closure calling logic from invokeMethod, as this makes for a cleaner separation.