I feel like iRacing's damage repair is (for the most part) a bit more reasonable. Hard hits do take likle 30 minutes to fix sometimes. Only part I find "off" is that a 30+ minute repair doesn't leave the car driving well in many cases. You'd think if they rebuilt the suspension or something that they'd have aligned it even a bit correctly.
So your PC can't maintain a steady 60 FPS if it drops down to 30 FPS via Vsync in some situations. "Steady except sometimes" means that it's, by definition, not steady.
The texture mods that you are using could be placing additional load or paging on the system, leading to missed frames and frame drops.
A background process could be stealing enough CPU time at the wrong moment to cause frame time to take too long, dropping the frame rate.
Again, it could be possible that for the races you're running, with the settings you're using, the mods that you're using, that your PC is just too weak and can't maintain 60 FPS.
Disabling vsync would help (albeit adding frame tearing) by ensuring that a slow frame doesn't immediately halve the frame rate.
If it's dropping to 30 FPS then you're not able to maintain 60 FPS in those situations. If you were, it wouldn't drop to 30. Additionally, dropping to a divisor of 2, 4 or 8 of refresh rate is a symptom of double buffered vSync.
The settings in nVidia control panel for vSync applies to OpenGL games, not DirectX. DirectX also has some problems with triple buffering in older versions of DirectX, in some cases it's just unsupported and in other cases it creates further input lag or dropped frames. It's also up to the game to support.
Those issues still sound like your computer being too weak for what you're trying to do. If there's a delay when cars join the track, that's resource contension where something needs to get paged in/out of memory and the system needs to wait for this to occur. Same thing if it happens in areas of the track.
Additionally becuase of how vSync work is that if it can't meet the refresh rate, it'll reduce to a fraction of the refresh rate to keep hitting frame timing. Triple buffering can reduce the major frame drops but it adds more imput lag. If you have it enabled and you can't maintain 60 FPS, then it'll drop to 30. If it can't maintain 30, even for a moment, it'll drop even lower.
It's a 8+ year old CPU. I just upgraded from a 4770 which was feeling very weak for most sims. Games like GTA are nowhere near as CPU intensive, hence why they perform fine with potato CPU + decent GPU.
A DDS file is a mod. If the base LFS texture is (for instance) a 256x256 pixel texture and you've gone and created a 1024x1024px DDS, you've increased the pixel count of that texture by 16 times, which occupies more memory. That could be the difference between "fits all the textures in GPU memory" and "GPU needs to swap textures from either disk (VERY VERY SLOW) or CPU Memory (SLOW)".
Essentially any changes to the base LFS install (outside of setups and translations) have the potential to impact performance.
That isn't a very strong PC. If it's running at 2.9ghz base clock, that's going to probably be a 2xxx or 3xxx series i7 which is 8 or 9 years old. 8 GB of RAM is also very little if you're running a plethora of background applications. The "lag spike" that you indicate could be memory needing to be swapped to/from disk causing an interrupt.
Your GPU is the most modern part of your machine, but the rest sounds very very old. I struggled with a full grid of AI on my i7-4770 because the CPU load was too high, but that's also a 7 year old CPU.
Yeah, it's the same with iRacing. They are using XAudio2 as a secondary audio engine which hasn't changed the sounds of the cars, but has added some nice ambient sounds around the track.
If something means 5 FPS lost for a high end computer, it probably means 15 or more for a low spec computer.
FPS matters. There's a reason why 60hz is the "minimum" for a monitor and not 30. There's a reason why VR demands 90+ hz displays. There's also a reason why people can notice a very clear difference between 60/144/244hz displays. Humans can definitely perceive much higher rates of change than "35" or else we would just set like.. 40 as a target and call it a day.
I still don't actually know what your point was for the screensavers. It's not a feature that would make LFS better in the ways that matter, nor would it be something that most people even leave enabled as it's just a waste of computing power that could be used for things that matter.
Package size doesn't matter in terms of computing complexity. You could generate textures and models algorithmically in code and have an incredibly small binary while still executing a complex world.
That demo is also from 2009 which is ancient at this point. Not to mention moving spectators does nothing to actually improve the parts that matter for a racing simulation. If you're driving, you wouldn't notice the spectators moving, and if anything you'd probably disable it becuase even 5 extra FPS is better than nonsense eyecandy.