Caching this function per request could improve the performance a bit, since the `readable_author` function is probably called a lot when used in a table (e.g. amount of rows per page * columns using the function).

You can probably cache it with [plone.memoize's view.memoize](https://pypi.python.org/pypi/plone.memoize#view-and-instance), because it stores the cache on the request object (so it the function is executed 1 time per request and we know it will not change within this request) – but I'm not sure whether this works in this context. It'd be great if you can try it out!