Game runs much worse than it did before

Hello, hopefully someone can help me with this

I had Beam.ng drive in 2013 and it ran at about 30-40fps - not good enough for most people but fine for me.
I decided to try the game again after seeing all the updates it got and suddenly it runs agonizingly slow at sub-20fps on settings that make it look much worse than before.
The part that confuses me is back then I had a terrible video card by today's standards - a GTX 260. I now have a GTX 950 and its running even worse than back then? I still have the same dual-core processor and 4gb of ram, but you'd think it would run at least as well. If anyone can help me with this I'd be very grateful.

Edited to add: I'm starting to think this may just be my old CPU not being up to it anymore. I tried freeroam for a while and it performed much better, staying in the high 20s on Normal. It only gets really bad when I try driving a car with lots of curves (Burnside) or do certain scenarios, like the one with the Moonhawk on Hirochi Raceway.

 

Pause the game (J) and check if your fps goes up.
If it does, it's a CPU issue. Shouldn't happen if it was working fine before.
If it doesn't, it's a graphics issue. Make sure your drivers are updated, try clearing game cache.

Also, do what Nadeox said.

 

Thanks for the replies guys, wasn't expecting anything to be honest
http://media.beamng.com/0pCSUqtGHkAhCKDy Gavril Pickup
http://media.beamng.com/MIejHifAZuu6Jaw8 Ibishu Pigeon
http://media.beamng.com/gTpNEu7GiabDmZYU Burnside Special

 

Thanks for bearing with me! Fixed the graphs. I notice my FPS getting steadily worse the longer I let it run. Not sure if that helps. Also, Ibishu Pigeon graphs were updating in very large chunks instead of smoothly like other cars.

http://media.beamng.com/jZCEZGcVHmm2rB82 D-Series
http://media.beamng.com/aJXemYgLUWfNtGdS Burnside
http://media.beamng.com/zkDPNJzYAIz4QvEs Pigeon
http://media.beamng.com/zX7ZMUqqnjFS5nqu T-Series
**edit: http://media.beamng.com/nJ5oeMWh9gnGk3lG T-Series collision off

When I disabled collision, my FPS with T-Series went from anywhere in the 20s to almost getting up to 60 while immobile.
Pausing the game with J gave me high 50s to 60.

 

I managed to get a constant, stable 60fps!
...with collisions disabled, resolution set to 1024x768 and graphics set to Lowest driving a Covet...but hey, not bad for a CPU originally launched in 2006 that you can now buy for $14!
Thanks for the help Nadeox and Bluescreen! Even if the CPU being the culprit was sort of obvious, I never would have found the collision toggle and gotten that massive 40fps boost from it without you!