Maybe if you told us what is was we could help out more. And maybe know whether it doing something it is not supposed to do.
Just a suggestion. Albeit a really useful one.
I know many times when I decided not to report something because I thought it was a "feature" of the software. And the one time I did report something I thought was out of the ordinary, it turned out it was supposed to do that!
So, long story short, what does the Cull Transients do?

A quick googling returns results related to measuring heat, nuclear energy, and controlling animal populations. Based on the name, however, I'm assuming that it shoos away some of the hobos that can nest in your video settings.

@ Nick

So would it be optimal to have this on normally or by default?

@ Pawea

Is this with the cull transients on, or just the normal "blast powder" optimization?

Great patch, I'm getting more frames now in FSC.

120 FPS in UFSC GO!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

er.... yeah sorry bout that ^, got a tad bored on my end after a long time at piano lessons :3

I've been playing a fair bit today, with the new setting enabled.

Hopefully these are helpful, here is a list of things I've noticed that I can't say as I've seen happen before, that I suspect have to do with it:

Occasionally loot from enemies that have died offscreen (killed by teammates or from ongoing damage) doesn't show up until well after the place where they've died has been on screen for a bit. This has caused loot to randomly appear a few times with no obvious source, rather than being on the ground as the spot it is located in comes into view.
Most obviously this seems to happen when dealing with Lumbers or Retrodes, it is basically acting like the game is invisibly going through the death animation after their death location has come into view since I didn't see them die before the loot shows up, even though they died a short while before. In some cases, it has played the death sound effect for them, so I've known what dropped the loot and gone to collect it only to see none there, then it pops into place when I'm quite close.

Had a lumber die without animating at all earlier. I've never seen a lumber simply vanish, and it hit me AFTER it was dead.
One moment I was fighting it up close, the next instant during my attack it was gone with a little poof of smoke, and a bunch of heat and crowns appeared and zipped over to me, then right as I got the last of the loot, I took a bunch of damage and was stunned, but not knocked back. It wasn't a lag spike so far as I can tell; it all happened without any real delay and everything was working and moving fine otherwise, I also got normal damage numbers until the instant it vanished and none once it was gone, unlike a lag spike where things normally just stop responding until it resolves itself. If it matters, it didn't die from a status effect and wasn't stunned (though the way I was instantly hit without it animating an attack was similar to the common stun bug.)
If I was to guess, I assume I killed it precisely AS it was starting its attack animation, so it died and attacked both with no animation, so I got hit after it wasn't there.

In a danger room, but so far nowhere else, every time I hit gun puppes with glacius charge bursts I was getting no damage numbers. No matter what the camera angle was from their location, there were no numbers, so it didn't seem to be the common issue where numbers appear to be very high above enemies from certain camera angles, or that they were out of view.
Everything else was working fine, so far as I could tell, but only that attack on gun puppies was failing to show damage values when they were hit.

Hopefully some of this makes sense in reference to the new changes and can help somehow. :-S
Otherwise, the game runs SIGNIFICANTLY smoother and faster. I generally found it pretty good before aside from the odd pause when things spawned in (which is gone) or framerate drop in freeze levels in particular (which also seems to be much better.)

I've noticed an issue with this feature in Lockdown.

Sometimes when you're running around with Striker dash you'll get hit by invisible expanded Polaris bullets, which is quite annoying. I'm guessing the speed of the Striker dash doesn't give enough time for the previously off-screen Polaris bullets to be rendered.

Aside from that issue I've been loving this new option, I still got a noticeable performance boost without it but with it turned on my FPS has reached levels that were pre-patch only obtainable in the guild hall. <3

I've been noticing that expanded pulsar shots that drift on screen from any side (especially from the bottom, because of the shorter FOV, though) don't appear even after they've exploded sometimes.

More than once I've had enemies erratically knocked about with no visual, or audio cues as to why - only to realize later that a teammate was firing his pulsar over my shoulder. Rarely, the explosion shows up after they reach maximum distance or impact something, but the shots are invisible until they explode.

So far, this is the only oddity that's really been inconvenient of everything I've noticed from the new option.

After playing for a bit with the option turned off, having it on makes a very significant difference in performance for me, so even with a few odd things going on, I think it's still worth it for me, and I'll keep it on for now.

While using the Cull, the vapor circle for shivermist, venom, ash, and voltaic disappears when you move to where it is off screen and then return to that area.
They still have the desired effect on monsters, but the visual does not return.

All in all, quite an improvement in performance.

*Edit: This happens when dropping a bomb and moving to where the bomb is off the screen before it explodes. Still makes the noise and affects monsters, but no vapor circle.

When you move quickly toward traps, sometimes they won't do the flashy thing that warns you the trap is about to activate.

Then the Cull Transients option basically means that every effect that occurs off-screen (for the player) is disregarded/ignored a.k.a. not rendered. It's still there, the game just doesn't make it appear on-screen. Of course therein the problem lays. If the aforementioned effect is brought back into the screen then the game must attempt to either a) work to bring it back, or b) just forget about the effect until later.

I believe that this description is the best way to think of the option, yes?

The "Cull Transients" feature was a phenomenal idea, and I commend OOO for making this optimization feature available. I run the game on a laptop with an integrated Intel video chip, making SK hardly able to run. I've always had <15fps at best, and I've always had the graphics on "Low" and "Compatibility Mode", which hardly helped at all. After the performance boost update, I hardly noticed any difference. With this feature, however, I notice my framerate go up significantly. Of course, due to the nature of my video card, I still get a few hiccups here and there, but it overall feels smoother. To even further praise this, the Lockdown map "Frostbite" is finally playable without an un-Godly amount of lag or frame drops. I have yet to dive into Ironclaw Munitions Factory, but I wouldn't expect it to play worse than before. Additionally, I feel that losing the ability to see off-screen effects (Haze Bombs, Pulsar shots, etc.) for a much smoother framerate is a fair trade off, especially on a cruddy computer like my own.

The only problem I have had with it is that I've had a few enemy Voltaic Tempests suddenly turn invisible.

Other than that, I went down to UFSC and DID NOT LAG HORRIBLY INTO A PIT FIRE!!!!!!

Yayz :3