I had been wondering about A-Life in this game, as it doesn't feel at all like it's working for me.
Here's a PC Gamer article about it. Apparently, A-Life 2 is in the game, but it's not currently working right, and they are working on fixing that.
And honestly, I'm not even mad. It wouldn't be a STALKER game if it didn't have bugs akimbo.
One more thing:
Make sure your video card drivers are updated.
I had been having severe stuttering with my 13900KF/4080. My drivers were only 2 months old, so I thought I should be good, but nope. Updated my video drivers to current (566.14 in my case), and suddenly the game runs smooth as silk. No stuttering, and no crashing.