The most obvious approach is to just constantly move forward and drop the enemies quick, but in order to clock fast times in, there is more to this game than just that. Here are some general tips to achieve faster times in speedruns of this game, applicable to all situations.

In this game you're not only limited by your own pace, your AI brother will stall your progress if he's too far behind, so you need to take some measures to move him faster as well.

To advance your AI brother faster:

• Try to kill all enemies before he reaches them. If he sees them, he'll enter his fight stance and takes a long time before he enters his walking animation again.
• If the enemies are out of your sight but not out of your brother's, try using dynamite to clear them.
• There are some checkpoints where he teleports to you as soon as you reach them. (A lot of them in Chapter IV, to be elaborated on)
• There are some areas on the maps where Thomas is supposed to help Ray climb up but Ray can get around them without his help.

To kill enemies faster:

• As Ray you have aim assist in dual wield mode. Take advantage of that and aim for the head. One precise headshot will save you a lot of time over spam.
• The classic gun is more accurate than other guns. Aiming for the head is especially worth it when you're using it as it's less likely to miss due to spread.
• As Thomas your rifle has higher rate of fire and reload speed. You can one-hit-kill enemies anywhere but the limbs, so aim for the body. Using the rifle as Thomas is often worth it even at close range.
• Use concentration mode (CM) effectively. It reloads your ammo (one gun for Thomas, both guns for Ray), so save it for when you run your guns dry. It slows you down, so try to use it primarily for reloads. More so on Ray, try to only use 1 mark per enemy to have as much ammo left in your guns as possible. In most cases it's worth to pop one guy to reload and continue shooting manually.
• Reload effectively. This goes especially for your rifle as CM doesn't reload it. Try to reload it when out of combat, ideally when you're not doing anything productive. Learn spots where you're waiting for something to do full reloads so that you know when you can afford to dry the rifle.
• Utilize dynamite. The dynamite is immensely effective in areas where there are enemies tightly packed together with limited ways to escape from it. You can often throw it in advance to clear an area you'll enter later and then fight enemies close to you.
• Learn consistent spawns. Knowing where enemies will appear out of and/or where they will path to will make you line up shots easier. Also knowing how many enemies are in a section will help you understand when you can move forward safely without your brother cleaning what you left behind.

To move faster:

• Avoid collisions.
• Not all enemies need to be killed. You'll mostly need to kill enemies that are an imminent threat, enemies that your brother will fight and those that are physically in your way. Avoiding them is a lot faster.
• Don't hold your rifle unless you're using it as you move slower with it.
• Keep sprinting and jumping. Reloading will cancel your sprint and sprint will cancel reloads, so keep that in mind. Reload when you're not moving.
• Shoot while moving if possible. Especially effective with a rifle.
• Learn the sings objectives are completed to know when you can move forward. Often it's a voiceline that will give you the green light much sooner than the objective indicator.