Answered by Sidi Mostafa Azzam
The Imam in our masjid does not give a pause after reciting the fatiha aloud, so I don’t have enough time to recite my fatiha, what should I do? Should I try to recite with him simultaneously?
It is normally detestable (makruh) to recite the Fatihah along with the imam. In the scenario you have mentioned, it becomes permissible, even required.
I remember Sheikh Nuh Keller asking this very question to the great scholar, Habib Zayn bin Sumayt (Mufti of the Shafi`is in Medina the Illumined), and Habib Zayn gave the above answer.
It is also addressed explicitly in Fath al-`Allam (2:468 (Dar Ibn Hazm)).
So recite your Fatihah while the imam recites his, but remember not to have any lengthy pause between the verses as you recite, since lack of interruption is a condition of validly reciting the Fatihah (as is mentioned in The Immaculate Raiment).
And Allah knows best.