Is it permissible to perform the Tarawih prayer two hours, or approximately, before the Fajr athan, or must it be performed immediately after the Isha prayer?

The time for Tarawih prayer extends from after the 'Isha prayer until the emergence of dawn. It is permissible to perform it at any part of this time. It is better for the Imam not to delay it so as not to make it difficult for the worshippers. As for someone who prays it in their home, they have the choice of performing it at the beginning of the night or its end.