No it doesn't. The longitudinal curve (acceleration) has a drop-off, but the lateral curve (cornering) forms a plateau with no loss of grip over the optimum slip angle.
Many many other sims do have this drop-off in the cornering curves, though, generally leading to the "unrecoverable spin syndrome" or "undriftability". Before patch T, LFS also had the drop-off, but not as severe as in many other so-called simulations, where the higher the slip, the more the grip drops and drops without end. Which is totally wrong.