odd performance issues

so i've noticed ever since i started picking up playing beamng drive again
that i'm having odd performance issues.
on grid map i get a solid 60 fps most of the times (depends on how crazy you make it offcourse)
but on alot of modded maps i've noticed weird drops going down to as low as 25/30 fps.
but for some reason 25/30 fps feels like 10 atleast
the fps especially drops when the tires are skidding i've disabled tire decals in the games files and that so far
has solved that issue for now till i find a permament solution
my rig consists of
2x xeon x5675 cpus totaling 12 cores 24 threads (i build this rig based for beamng for the most part)
gtx 1060 6gb
and 38 gb of ram
i thought maybe beamng being installed on one of my hdd's caused it so i moved the entire game to the 128gb ssd windows 7 is installed on (windows 7 sp1 updated with 2019 patches)
i've got the april game ready drivers from nvidia and all other drivers has been up to date
when i open the ingame graph i dont notice any weird spikes or anything (i'll make a recording of the graph when i get home)
before i quit beamng i had no performance issues at all regarding these issues.
other games run at max settings perfectly (forza 3 and 4 for example. 75 fps maxed out with near none drops under 55)
any help with this would be appreciated
thanks in advance

 

There was at least one Nvidia driver version where their driver added to CPU usage a lot and could cause performance issues with systems which single core performance was not top of the line.

I'm using this driver now as newer Nvidia drivers are less optimized for older cards like 1050Ti or 1080 and have zero issues with them so far, but bit increased performance, so worth to try them.
https://www.guru3d.com/files-details/geforce-399-07-whql-driver-download.html

Also you can find new option from graphics settings, hardware accelerated UI, that might be worthy to test.

Usually most odd performance issues are because game needs fast single core performance because graphics, lua etc. So especially when putting different cars on map with high graphics enabled you may find that what your one core can do is limiting more than amount of cores you have. That will also show up with lowered GPU usage, so when you check ctrl+f fps counter you can see GPU delay is very low, like 1.0 or less and fps are dropping.

Normal graphics, then select custom, set high texture and 16x AF so game looks better, that can save some CPU time if you will face such fps dropping, reflections and ssao together like also cause bit of extra load as everything gets repeated so load gets multiplied and with really fast GPU that can handle such, CPU single core performance can become limiting factor.

Game was improved a lot in that when Italy came, also in 0.16 improved physics performance, so they keep fiddling with the stuff.

Now with some mod maps situation is different again, Shuto expressway for example has quite heavy single core load, some maps use meshroads made in editor and those traditionally have had caused very high single core load when skidding.

Then for some game is not running as well now than what it was in 0.15 version, there has not been clear reason for this, but it can be several quite recent GPU drivers from Nvidia have something causing the issue, that is why I recommend to try that much older driver.

There can be of course plenty of other reasons, but something to get you started with.