Some (not all!) game settings carry over from Instant Action to the campaign, allowing significant time savings. You need to change the settings for each game mode separately. They can be accessed by going Instant Action > (Choose gametype) > Game Rules.

I'll list the most important changes below. If you can't find them, make sure you have 'View Advanced Options' tick marked.

Assault: Spawn Protection Time - 30.00

Deathmatch and Team Deathmatch: Time Limit - 1 (this will only work for for the last 2 maps) Spawn Protection Time - 0.00

Double Domination: Time Disabled - 1 Time To Score - 0

Bombing Run: BallLauncher drains Translocator - OFF

The Assault Spawn Protection change allows safe passage to most objectives as long as you don't use your weapons.

Domination changes allow scoring once per second, making it possible to finish some maps in under 20s.

Bombing run changes allow the usage of the Translocator right after shooting the ball, increasing the speed with which one can get to the enemy goal.