Cannot get a picture object from the input parameter, error occurs on region checkpoint tests

Yup, you got it.  Extended Find does go through a search process which may take some time.  It is also possible that the object you have mapped may have changed it's identification properties.

I do use Extended Find for some things but usually I map everything and only use Extended Find as needed.  My suggestion for you is that, for the object in question, add additional parent objects in your mapping to reduce how far down the tree Extended Find has to search.  This will resolve the issue you're currently having as well as have the effect of improving your automation performance.