My assetto corsa freeze frames every half a second or so, on ly recently though

[Tadpol Milk]

very recnetly i notcied that after a couple of seconds of driving (depending on track sometimes instantly) the game freezes for like half a second and resumes. this happens every second or so and its very annoying and noticable.

I have no idea whats causing it i have chnage graphics settings, lowered my game to 5Hz and still it happens

i have seen no answer to this, but the weird thing is when i benchmark with 24 cars at spa the game runs a smooth 100fps no stuttering?

please help this is so annoying and i see no other solution