Well, I might be late for writing this thread but anyway. I'm gonna advice some solutions to increase FPS
1st step: Update your drivers
You can update your drivers with Driver Booster
Driver Booster link:
2nd step: Clean your PC and delete useless applications
I advice you to use Ccleaner
also I advice you to delete useless files: Win+R > temp / %temp% / prefetch delete all files on those folders (I do that thing every week and I believe it works)
Ccleaner link: https://www.ccleaner.com/
3rd step: Close applications that you don't use
You can do that by Task Manager
4th step: Tweak your MTA and NFS:SA settings
for MTA settings: decrease your resolution
(I find 1360x768x32 enough and fine), set FX Quality to Low, turn off anisotropic filtering, turn off anti-aliasing, and disable volumetric shadows and tyre smokes etc.
for NFS:SA settings:
F11 >Video > decrease Far Clip Distance x10 (I advice 60) and Vehicles LOD Distance (60 seems fine), disable Blur mode, set vinlys quality to medium or else (not so effective) , F11 > Gameplay > disable driver name and disable crew logo (actually changing the crew logo size works too), F11 > Audio > Car Sounds Settings > turn off the hear other cars (3d sound)
5th step: Use HUD wisely
turning off HUD increases your FPS as well so doing that in races is might be a good choice.
That's all, I hope it did solve your problem. Thanks for reading.