Does some parts cause more "lag" then others?

[Sokar408]

Basically, is some parts more performance demanding then others? The reason I ask, is that I'm always so anxious about making things, because I'm afraid the turn out will be impossible to use, due to low FPS. Now my computer is a relatively high end machine (CPU: Core i7 4790K. GPU: GTX 970. Mobo: MSI Mpower Z97. etc.), but I once tried to download one of Overfloaters planes, to test in with FAR (Which as expected, didn't go well xD), and my FPS tanked to unplayable levels.

Now in that case, I'm assuming FAR is the cause, making more demanding then stock (assumptions, I have many), but beyond that, is there parts I can use without too much fear of FPS tanking? Is physicsless parts less demanding? Questions questions questions! xD

[DMSP]

I am not sure if certain parts cause more lag, but MORE parts will. For example, Overfloater's SSTOs have many parts, and they lag a lot. Mods add to lag (From my experience)

Hope it helps.

[Starman4308]

If your CPU is tanking, it's probably more number of parts than anything else. FAR does require additional compute time, but not much: again, it's number of parts which kills you*. Engines are more demanding than other parts as well, because they have to scan fuel tanks each tick. I'm not 100% sure how the game engine handles physicsless parts, but I'd assume they still have to have some physics calculations run on them.

*I know physics takes more than O(N) time for N parts: I'm not sure if it's O(N*ln(N)) or something else, but the physics time per tick goes up faster than the number of parts.

[Claw]

Lights, as discussed in this thread, can cause a slowdown in gameplay. So if you're using a lot of lights, it can cause a lot of lag.

Also, if you're generating and consuming a lot of resources such as Intake Air or Electricity, this seems to slow down the game a bit more than having an equivalent number of non generating/consuming parts. Most specifically the Intakes and associated Jet engines seem to be prone to this. This is likely due to the fact that the consumers search all over the ship for it, instead of just taking it from the first part they run into during searching (such as with liquid fuel & oxygen). So if you have a lot of engines, and a lot of intakes, there is a lot of searching and calculation going on.

Cheers,

~Claw

[SpaceJuice]

Ksp runs on a unity engine, meaning polygons are needed to form parts. The more physical details on a part means more polygons to be be a part. Unless the texture is detailed.

[Norcalplanner]

I remember reading in another thread that the shielded docking port and claw both caused a big frame rate hit.

[Vaporo]

I remember reading in another thread that the shielded docking port and claw both caused a big frame rate hit.

True. I made a bug report thread about the claws a few months back (I like to think that I am the discoverer of this bug, but probably not). I have no idea why it happens, but it doesn't seem to be physics-related or polygon-count related. They just cause a ton of lag.

[SRV Ron]

Want to test lag? Build a rocket using a stack of 100 Round 8 fuel cans. Then, try flying it.

[MartGonzo]

low FPS on that rig?

holy ****

That's got to be down to mod issues, how many are you running?

[Starman4308]

That's got to be down to mod issues, how many are you running?

Unlikely, actually. Mods mostly ping on RAM. If he were having RAM issues, he wouldn't be lagging, he'd be crashing. There might be the odd mod which requires a lot of CPU time, but most are fairly minimal.

The possible causes of slow KSP are either that his GPU is having trouble rendering stuff (very unlikely with his rig), or that he has a whole bunch of parts. Physics time increase faster than the number of parts, and since Unity physics is single-threaded, that means he can only set one CPU core on it. His CPU is, well, faster than I thought CPUs got without overclocking, but he's still going to run into physics problems when he starts using a lot of parts. At an extremely vague guess, I suspect he could do 500-ish parts without a drop in performance. 1000 parts, and each tick would take significantly more than 2x what it took for 500 parts.

[MartGonzo]

Unlikely, actually. Mods mostly ping on RAM. If he were having RAM issues, he wouldn't be lagging, he'd be crashing. There might be the odd mod which requires a lot of CPU time, but most are fairly minimal.

The possible causes of slow KSP are either that his GPU is having trouble rendering stuff (very unlikely with his rig), or that he has a whole bunch of parts. Physics time increase faster than the number of parts, and since Unity physics is single-threaded, that means he can only set one CPU core on it. His CPU is, well, faster than I thought CPUs got without overclocking, but he's still going to run into physics problems when he starts using a lot of parts. At an extremely vague guess, I suspect he could do 500-ish parts without a drop in performance. 1000 parts, and each tick would take significantly more than 2x what it took for 500 parts.

Good point, it's hard to imagine what sort of craft this chap is building that could be causing lag on a high end rig like that

[cantab]

my FPS tanked to unplayable levels.

The big question: Which is? As in, are you regarding anything less than rock-steady 60 fps unplayable, or are you considering 12 fps not a problem?

Also, roughly what's the Physics Time Ratio? Open the debug menu with Alt/RShift+F12 and click debug stats, and you can read it off the top left corner.

[panzer1b]

Intakes, and engines seem to have the most lag (they need to calculate thrust, check resources, and intakes also seem to have extra drag calculations due to dynamic drag or so id guess).

RCS thrusters especially in large numbers are also a major problem (since they have multiple nozzles, and the RCS seems to be somewhat resource intensive at least relative to most other parts)

A few tips:

When possible, replace 2+ parts with 1 larger pat (say kerbal x rocket, why not swap some of those half sized tanks for a orange tank).

Minimize engine count especially when the craft ittself is already high-part count. Even if it means sacrificing a small amount of dV, or having slightly longer burns, use the minimum amount of engines to get the mission done.

Avoid a crapton of wings, they seem to increase lag especially in large numbers (id guess lift calcs take some power).

Avoid using claws when you dont need it (ive heard it can kinda lag).

Use physicsless parts when possible for utility applications (use a radial mount massless battery instead of the in line ones, or multiple 1x1 solars instead of a larger array). While im no fan of anything being weightless, as is stands, using these parts does nothing but improve the game's FPS. Physicsless parts still add lag (so having 2000 struts is still gonna be slow down the game), but the amount of lag the add is a small fraction of normal parts.

[SpaceJuice]

True. I made a bug report thread about the claws a few months back (I like to think that I am the discoverer of this bug, but probably not). I have no idea why it happens, but it doesn't seem to be physics-related or polygon-count related. They just cause a ton of lag.

The lag is probably from the part models. Like the animations and electricarge made from rockets.

the lag in the claw is from the part .CFG model for it to Atach to something.

Edited December 13, 2014 by Spacejuice