Which mods are CPU heavy?

[CanOmer]

I am not new to KSP but new to modded KSP. After I discovered mods are real game changer I added a lot of them (nearly 50 mods!)

My specs: Core i7 920 @3.6GHz GTX 1080, 12GB DDR3, SSD and I use Windows 10 with 64bit KSP on max settings at 1920x1200 resolution.

Mods I use (I used CKAN for all of them):

With these mods in the game my main limitation is large vehicles 150+ parts drops FPS. It is related to CPU. Now, I want to know which mods add to CPU load which cripples simulation speed.

An example for my experience: 161 parts shuttle at launchpad (PHYSICS_FRAME_DT_LIMIT = 0.01):

CPU usage: 33%

GPU usage: 41%

Memory usage: 6.7GB

I want to use my GPU with visual mods but don't want to use CPU much which cripples simulation speed.

Edited December 27, 2017 by CanOmer

[ARS]

Most graphic mods usually the most resource-intensive ones, being the first contender of CPU heavy mod. It's also the reason why KSP graphic is fairly simple, to make room for complex calculations while still keeping enough resource for making the game playable without overtaxing the graphic engine. The second contender is parts pack which contains a lot of parts since the game needs to load each one of them, so the larger the number of parts available, the longer it took to load. But even without mods, if your ship is complex enough, it's still able to cause your performance plummet

[CanOmer]

I want to use visual mods which use GPU rather than CPU. I tried Spectra, Astronomer's Visual Pack alongside with SVE and all visal submods which they require or recommend. But I don't know sure what should I choose.

Also I want to know if other minor-visual and non-visual mods are CPU heavy? (For example distant objects or realplume, mechjeb, USI-LF...etc)

Edited December 27, 2017 by CanOmer

[Shadowmage]

2 hours ago, CanOmer said:

With these mods in the game my main limitation is large vehicles 150+ parts drops FPS.

That is about normal.  With or without mods.  On a highly overclocked i5, even when running only stock, right around ~120 parts is where I start getting FPS slowdown from CPU bottleneck.

KSP is CPU limited by part-count.  And single-threaded. Nothing you can do about it.  More parts = lower FPS.

You can try out part-welding -- reduce the part-count on the vessel by combining some of them.  Or you might give SSTU a try, as it is specifically intended for 'low-part-count' vessels -- e.g. a fully functional shuttle stack in SSTU is like maybe 25 parts, with most craft coming in far lower than that. (see signature for links)

 

As to your question 'which ones are CPU heavy'?

• Mechjeb
• SVE (and GPU)
• Scatterer (and GPU)
• EVE (and GPU)
• Kerbal Engineer
• USI mods (lots of plugin code in them)
• Chatterer (sounds are purely CPU driven)

Basically pure 'parts' mods should be fine.  Any mod that includes custom plugin code is highly liable to increase the CPU load on the game when using that mods' parts.  Any 'visual enhancement' mod will hit both the CPU + GPU due to how they are scripted (lots of CPU based C# script to drive the GPU end of things; so it impacts both).

You're not really going to find any 'pure GPU' visual enhancement mods for KSP (that I'm aware of).  Too many limitations in how Unity is structured, and how KSP is built on top of it.

[CanOmer]

Thanks for the info. So, if you compare, which big visual mods use considerably more CPU than other visual mods? (Spectra, SVE, AVP, KSPRC...etc) Or are they all similar? Does texture size choice make difference on CPU?

[Galileo]

4 minutes ago, CanOmer said:

Thanks for the info. So, if you compare, which big visual mods use considerably more CPU than other visual mods? (Spectra, SVE, AVP, KSPRC...etc) Or are they all similar? Does texture size choice make difference on CPU?

They will all be the same due to the fact that they all use the same dependencies (EVE and Scatterer) 

texture size does make a difference, SVE has a low medium and high resolution texture pack for those who need more performance, but the issues lies with volumetric particles in EVE. They are resource intensive. 

[Starman4308]

On 12/27/2017 at 8:09 AM, CanOmer said:

I want to use visual mods which use GPU rather than CPU. I tried Spectra, Astronomer's Visual Pack alongside with SVE and all visal submods which they require or recommend. But I don't know sure what should I choose.

Also I want to know if other minor-visual and non-visual mods are CPU heavy? (For example distant objects or realplume, mechjeb, USI-LF...etc)

Graphics will use both. You need the CPU to send rendering instructions to the GPU. While increasing settings usually doesn't hit the CPU much, because you're saying "render a bigger screen with these high-res texture files instead of these low-res textures", adding effects can be a non-negligible impact on the CPU, because you need to send a bigger package of instructions to the GPU.

I suspect FAR can be another CPU-heavy culprit due to a lot of custom aerodynamics code.

[Jas0n]

Personally, I've found that RAM is far more limiting for KSP than CPU, but maybe that's just because I only have 8GB of RAM.

[Kerbal101]

Following may influence performance: parts with excessive polygon count, part count in ship (doh), part joints when physical simulation is active, open docking ports, lighting on parts, volumetric clouds, additional conditional logic, suboptimally scaled textures
Expensive on RAM: extra textures, sounds, any extra content within Gamedata

So, any additional mod will increase RAM usage, but depending on what it does - it may improve or decrease performance.
Some examples:
Mod that adds equal or larger parts with lower poly count than existing parts, will improve performance because there will be reduction in geometry detail, less drawing calls, less physic calculations.
Mod that overrides textures will increase RAM and may increase CPU usage, but may improve fps due to less downscaling of larger texture, using lots of smaller duplicate high-er detail textures instead.

How the mod set affects performance, is best done with own benchmarking.. Start with small amount of mods, prepare a complex ship for example in kerbin orbit (a), on landing pad(b) and  in orbit around Mun(c). Make a save.
Then do a screenshot of gamedata folder and add a group of mods. Compare the difference in these scenes and if there is performance reduction - bissect to problematic mod by pulling the mods from the recent batch.
If there is no problem, make screenshot of gamedata and proceed to add another group of mods.

In my own testing, I have discovered quite contradictory things. Mods that improve visual detail of parts or textures, do not necessary reduce or may actually improve performance.
Mods that introduced parts with better properties or lesser polygon count, allowed to reduce total part count for the ship and improve fps.
The welding mod did not affect performance at all, because while it decreased physics calculation - the geometry complexity remained same: parts were merged, but graphical models were not.

As for ships, I recommend to build ships with less part count, using parts with less geometrical detail in themselves.
The most prominent example is stock Z400 battery. Building a 100x block will destroy performance.
A mod, such as "Near Future Electrical" adds low-poly 10k battery and nuclear reactors, both of options will have much less drastic effect of fps.

Finally, i7/920 is really not good at single thread work. I am saying this, because I am using somewhat similar gen. CPU. An upgrade would be good, the geekbench (single thread column) or passmark(single thread column) have good comparison tables.