Injustice 2 has a 30 FPS cap that is applied to menus and all in game cinematics, this includes intros, victories, clashes and supermoves. Using I2Hook, it is possible to remove this cap and enjoy the game in 60FPS all the time.

You can download latest I2Hook (60 fps patch only) release from GitHub:

Go to your library and find Injustice 2. Right click on game name and select Browse local files

This will open an explorer window with your game folder.

Go to Binaries and then to Retail directory. You will end up in Injustice2.exe location.
Extract downloaded I2Hook archive here and you are all set.

Make sure I2Hook.asi and dinput8.dll are near Injustice2.exe!

Correct installation example.

You might need to turn off in-game V-Sync if 60 fps patch is not applied.