one of the players jumps on the rails, then jumps on top of a train and then jumps on an invisible wall (your best bet it to aim for umbrella logo and be in the middle of the train), then you run along this wall and jump down to the elevator which must come up after you press a button, then the 2nd player triggers the elevator, you move to a platform and then you jump right below the elevator, aiming for the exit and the second player who's on top must kill himself in order for the first player to continue it is risky for casual/normal speedruns but for professional/veteran it is less risky since if you fail you can suicide

possible fails: if you overshoot the jump on the invisible wall from the train, you'll still get a time save (not as much of course) but at least you won't lose any time at all (UPD: actually I just realised that this kind of time save will work perfectly for solo runs!) if you won't reach the invisible wall, you'll just fall on the train tracks and thats pretty much the end of your run if you're running on low difficulties and cant suicide (BUT if you position yourself like I did on the video, you pretty much can't miss the jump)

in the end this skip saves more than 2 minutes, I'd say it's a must-do on every coop run but of course the downside is that it can't be done in solo runs (unless if you won't go for a jump down to the elevator and just run to the button like I said above)

UPDATED FASTER AND CONSISTENT VERSION IN THE COMMENTS

Basically the trigger to activate Birkin sequence is at around the same place where the soldier who's sitting closer to the edge of cover tries to melee you so if you allow him to melee you, you will enter an animation that you can't escape and this allows you to stay behind or in those spawning boxes which are preventing you from going back on birkin sequence and therefore the game respawns you next to the door I accidentally did that on my practice speedrun attempt when I haven't killed anyone and just tried to run past but the guy knocked me with melee and I couldn't replicate it for a lot of time and now I finally understand what you need for it atm I dont know will it work offline or will it work consistently but im pretty sure that answer to both questions is "yes"

Literally every time im trying a run with my friend we always get softlocked on one particular moment, when you go to the safehouse and trigger that tyrant cutscene it just doesn't want to work as intended resulting in a softlock, we're so tired of this shit, we cant complete a run for like 3 days already just because this game keeps softlocking us here https://imgur.com/a/L85BmHT

Latest steam version runs very poorly for me while an old pirated version runs very smooth, can I use it for speedrunning (in solo of course)?