1)
What should Hashem hasten?
1.
Malbim: He should hasten to hearken to David, and to save him.
2)
What is "l'Tzur Ma'oz"?
1.
Radak: It is a fortress in which my pursuers cannot catch me.
2.
Malbim: Even though now I leave a fortified city, You will be my strong fortress. Even though now I leave Metzados in the Midbar, You will be for me Beis Metzudos, to save me.
3)
What is "Beis Metzudos"?
1.
Radak: It is a strong tower, like "v'David Az ba'Metzudah" (Divrei ha'Yamim I, 11:16).