Kelly Hu was 42 in Phineas and Ferb: The Movie: Across the 2nd Dimension when she played the character 'Stacy Hirano (voice)'.
That was over 13 years ago in 2011.
Today she is 56, and has starred in 64 movies in total, 24 of those since Phineas and Ferb: The Movie: Across the 2nd Dimension was released.
In Phineas and Ferb: The Movie: Across the 2nd Dimension, I think Kelly Hu looks: