Thanks to @pturmel recommendations I can confirm that the order of magnitude is correct when moving away from reading AOIs and only reading UDT’s.
What we do is have an AOI that has an In/Out Parameter that is the HMI only UDT. All other tags that are needed in the program outside of the AOI originate from the AOI that way we can differentiate between the two when looking at the code. It has changed the load factor and mean response on logix PLC’s in some respects to a 10th of what they were before. Also being smart with tag groups on the tags. See: CLX performance for information on that.
For default values @jlandwerlen, we have an init bit in the AOI that is default low and when that init bit is high that we set default values in the HMI UDT within the AOI and then set that init bit low.