Hi Brian, there is an update to Flow in the Dec-1 v5 beta to make it use a fitting tolerance that is based on the smallest feature of the object being deformed. That's instead of a fitting tolerance relative to the whole source object's bounding box.

That is likely what is making it take longer, but it should also be generating a more accurate end result.

Here's an example - in the attached file if you use Flow on the thin cylinder:


In v4 and the Apr-13 v5 beta you get a result like this with pretty easily seen deviation:


Here with an exact circle on top:


But with the new Dec-1 v5 beta you get this more accurate result:


- Michael