This scene is using a Legendary Relentless Assault Rifle. Note how the AP drains per shot, but then refills when I use a critical. Also, this character has 175 AP, so the firing cost seems small, but it's actually a bit more than you might think.





V.A.F.S. is the VaultTec Accelerated Focus System.

It's an alternative way to spend your AP during combat that is more engaging and fun than watching V.A.T.S. cutscenes.
Simply use the [VAFS] Focus Toggler (found in the AID inventory) to accelerate your senses to a superhuman level, slowing your perception of time and allowing you to react faster and more accurately than your enemies. This costs AP over time to maintain, but ALSO costs AP per attack you make, so make your shots count!

The amount the world slows down around you scales with how perceptive you are. Many bonuses that apply to V.A.T.S. now also apply to V.A.F.S. so you don't have to feel like you've wasted any perk points or stats.

Not only can you slow time with V.A.F.S., but you can also use criticals. If you like tactical crit usage you'll love this. You'll now be able to use a critical at any time by using the [VAFS] Use Crit item. Fire immediately after usage to hit your enemies for critical damage! Crits build up in the background with every hit you make, whether inside V.A.T.S., V.A.F.S., or neither. Unleash them when you need that boost in combat.

Perks:

Mysterious Stranger: The Mysterious Stranger will appear occasionally at the start of V.A.F.S. when the player is in combat. He will engage targets for the duration of V.A.F.S. and then disappear afterwards.
Better Criticals: Works with criticals provided by V.A.F.S.
Critical Banker: Determines the amount of V.A.F.S. criticals you can hold. Each rank is 1 extra, just like vanilla criticals.
Grim Reaper's Sprint: Has a chance to restore your AP on kill during V.A.F.S. now. Rank 3 has a chance to give you a V.A.F.S. critical charge too.
Four Leaf Clover: Chance on any hit during V.A.F.S. to give you an extra crit charge.
Blitz: Now increases movement speed dramatically during V.A.F.S.
Quick Hands Rank 2: Reloading in V.A.F.S. is much faster. Faster than normal reloading even.
Awareness: Humans and creatures will be highlighted in Red/Green/Blue if they are Hostile/Friendly/Dead respectively. This can be toggled on/off in the options holotape.
Sniper Rank 3: While aiming with a scoped weapon (this includes rifles, pistols, even automatics), V.A.F.S. will be 40% slower.
Penetrator Rank 1: Enemies will emit red sparkles that can be seen through walls within a short distance during V.A.F.S. Can be toggled in the options holotape.
Penetrator Rank 2: Weapons that fire .50 Cal or 2mmEC rounds will penetrate objects and hit targets hiding behind them. Acitve all the time, not just during V.A.F.S.
Killshot (MacReady's companion perk): While aiming with any weapon, V.A.F.S. will be 20% slower.
Isodoped (Hancocks companion perk): Increases critical charge rate by 20% while irradiated.
GunFu: Works very similarly to vanilla, except it counts targets during one V.A.F.S. session.
Concentrated Fire: Works in both real time and V.A.F.S.
Awareness Rank 2: A perk that you can take to simply increase the strength of the slow during V.A.F.S.

Ricochet Rank 3: To do, unsure on implementation currrently.

Penetrator Rank 2 in action:

It allows yo to shoot through objects like that steel beam.

Legendary Effects:

Lucky: V.A.F.S. Criticals will do more damage and charge faster.
Relentless: Will refill AP when you use a V.A.F.S. critical.
VATS Enhanced: (Weapon version) Now called VATS/VAFS Enhanced. V.A.F.S. will be 20% Slower if you activate V.A.F.S. while wielding it. It also costs half the AP to fire during V.A.F.S.
VATS Enhanced: (Armor Version) Now called VATS/VAFS Enhanced. Also reduces AP costs to fire weapons in V.A.F.S.
Freezing: Will freeze targets if you use a V.A.F.S. critical.
Enraging: Will frenzy the target of a V.A.F.S. critical.

Items:

[VAFS] Focus Toggler: New item that you use to toggle V.A.F.S. on and off. Hotkey for easy use.
[VAFS] Use Crit: New item that you use to activate V.A.F.S. criticals. Hotkey for easy use.
[VAFS] Manual and Options: some ingame use tips, as well as all in game V.A.F.S. options.
Jet: Now increases movement and reload speed on use, instead of slowing time. WOrks well in combination with V.A.F.S.

Options Holotape:

There is an included Holotape with the mod called [VAFS] Manual and Options. It has a reference to explain some of the technical bits of using VAFS and a few pointers too, worth a couple minutes to read. It has options inside for turning the benefits of Awareness highlighting on and off if they aren't to your taste. Same with Penetrator vision. You can also toggle the popup message to let you know how much the weapon you've equipped will cost to fire in VAFS, and the message that periodically reminds you that you have crits. All the things that I thought might annoy some people, but help others.


Required Mod:

HUDFramework by Registrator2000
This is required for the new critmeter to work. You may choose to not use the critmeter if you don't want to install it.

Recommended Mod:

FO4 Hotkeys Mod by Registrator2000
Quickslots can't be used while aiming or looking at lootable containers, and this cramps the flow of using crits a little bit. Feels better if you assign the items to the hotkeys provided by he FO4 Hotkeys mod.

Note on Scripts:

A couple people have asked how "script heavy" this mod is. I'm proud to say that it's not heavy. There are a couple of heavier scripts involved with figuring out how much AP to subtract from the player, and which weapons qualify for Penetrator, but these fire on the infrequent OnItemEquipped(), and only for weapons. The two fastest firing scripts, for any actor OnHit() and the OnAnimationEvent() for "WeaponFire" only during VAFS are super small, 10 and 5 lines respectively. The heavy lifting is done when the player equips the weapon, and these fast firing scripts reference the saved results efficiently. I've tested extensively and I've found no performance issues on my midrange laptop. None of my XB1 users have complained at all either.

Immersive HUD (iHUD) Compatibility:
Get the "iHUD Compatibility patch" from this page made by Neanka for iHUD. It will prevent iHUD from influencing the meter. Fret not! I've added some iHUD-like features to the meter to give you control of when it is visible. Just go to the holotape options section, then deeper into the "configure crit meter" section for visibility options.

If you still have issue with iHUD and the meter, you must set the Compass HUD element to always visible, and the crosshair to always visible.

Sim Settlements Compatibility:

 There is an issue currently between  Sim Settlements, HUDFramework, and VAFS. Due to this issue, if you are running Sim Settlements, then HUDFramework becomes required for VAFS to work. If Sim Settlements is loaded and HUDFramework is not loaded, VAFS will fail to function. I'm working with other mod authors to try and resolve this problem.

General Compatibility:
For Far Harbor DLC users, you must use the Far Harbor compatibility patch in optional files or a few perks will be bugged.
For Nuka World DLC  users, you must use the Nuka World compatibility patch in optional files or a few perks will be bugged.
VAFS modifies a few perk descriptions and may cause conflicts with other mods that modify perks. To fix this, simply load VAFS BEFORE any other perk modifying mods. You will lose some VAFS-specific perk text, but otherwise all gameplay will work properly.
The mod is now compatible with all mod-added weapons!
VIS naming patch for the AID items can be found here: http://www.nexusmods.com/fallout4/mods/18098/?
All other mods not mentioned here should be compatible. If not, let me know in the comments and I will reply.

Known Issues:

May interact weird with other slow time effects such as Nerd Rage, Deadeye, and the Legendary Armor piece effect. If one of these happens during V.A.F.S. it will override the V.A.F.S. slow. If you deactivate V.A.F.S. it will end the slow component of those effects too. I recommend not using these effects until I can develop a fix.

Special Thanks:

To the members of the Fallout Mods Discord, they helped me with a lot of questions and testing:
ShatteredSteel
AI-TV
Sepherch͜orde
TheNewScrunt
BlackLotus923
Dogtoothcg
Rebsy