A quick test shows that it works reasonably fast if you strip it down to something which only works if the
Alignment inspector is already open.
(The pair of illustrative macros attached below aim to be more ambitious and test if the inspector is ready, and summon it if not, but they end up searching for the image 3 times, and I find them noticeably slow ... Over-engineered, in short. Sometimes keeping it simple really does work better :-)