Why does my FPS crash from 140 to 50 in Need for Speed night scenes?

I've had enough; I bought a 90-series card only to have the FPS drop from 140 to 50 in the neon streets. I tried enabling 'Overclock Mode' in the driver; while the peak frequency rose, the drops became even more severe, which was an infuriating reverse-optimization. I used the GamePP BIOS Load-Line Voltage Adjustment Wizard to manually lock the core voltage at 1.12V. Frame generation time converged to 7-11ms per RTSS monitoring and core temperature stabilized at 74-79℃ per AIDA64.