There is no way to completely remove the framedrop issue with your spec.
But, you can improve your fps to a "playable" rate.
What you do in the graphic options is basically turning off every bits of graphical ehancer
(Skies, Shadow, Trees, Flags, Rubbers, Texture Filtering, Reflections, User LOD to lowest possible, Dust LOD to lowest possible, Putting textures to low res and Skins to compressed and switching Z-Buffer to 16, All Mip bias to 0)
Once you're done with those head to Miscellaneous and turn off Vertical Sync, add more sound lag, disable multiplayer speedup option, and set Dynamic LOD Reduction to 1.
Setting your resolution to a somewhat sickening 4:3 might help.
Another neat way is to set your Windows appearance to Performance mode via Performance Information And Tools' sub-menu, Visual Effect
We both have the similar spec, only to be differ by a slower CPU speed yet i can race fine with the system handicap i have so i don't expect your fps to be worse than mine