I believe the changes in TC10 that "possibly" affected your performance were changes to make the refresh parameter (defaulted to true) actually work. So the refresh of the FindChild, Find, FindAll methods could be the performance hit you are seeing. More than likely you are going to want the refresh working vs. having it work faster and possibly miss objects , properties, etc. What I would suggest doing is narrowing down your FindChild search criteria by specifying a process, form, and/or setting the number of child objects to be searched(using the Depth parameter) to a lower number. If you absolutely want it to work like previous versions try specifying no refresh like so:
TestObj.FindChild(PropNames, PropValues, Depth, false)
^
^
^
^
