So this isnt a question perse its more of an observation form 3 days worth of testing
I started a new save 120+ fps stayed like that for most of my build
Then i started messing with trains
Built one looped track with a Locomotive and 3 Train carts to haul all my coal back to my steel plant Fps stayed 100+fps for hours of play never dipped to bellow 100fps
Then i got oil and caterium decided that ill use train to get those resources back to base
I opted to use the the non looped tracks that are station dead ends (so Loco-cart-loco facing in opposite directions)(track where not connected-one train per track none of the other trains could see those stations).
Then 2 hours in my fps dropped to 80fps (i thought nothing of it becuase that is still really good fps)
Enter the oil era- Setup oil pumps and 6 refineries oh and a enclosed dead end station setup to get plastic to my base .
Low and bahold 10min in my fps drops to 50fps (still not concerned) another hour in my fps in below 30fps
This is where i decided to to push it and see what happens, I let it run for 3 more hours Fps drops to 15
At this point I save my game and exit to desktop, run the game agian reload and boom back at 60 fps
Now come the part where i tell you that i know reloading clears what ever cache has built up in the memory
So after i load back in and get decent fps i decide to delete those double ended loco setups
I save right there and reload and Bam back to 100fps
so my conclusion is that it has something to do with the double ended trains i cannot be sure of this till the Dev Team takes a look at it .
This is just my observations i will continue to keep this updated while i search for that dreaded FPS sink
Satisfaction Labs Technician