Why does my FPS drop from 90 to 30 during intense combat scenes?

The moment an orbital strike hit, my screen practically froze—a total nightmare. I tried lowering the shadow quality in-game, but it only gained me 3 FPS and made the graphics look lifeless. I used the GamePP Power Plan Switcher to force 'High Performance' mode and bumped the fan start voltage to 0.7V. This stabilized the CPU frequency at 4.2GHz per CPU-Z, keeping FPS between 75-82 per RTSS, while case temperatures stayed within 45-52℃ per Sensor and CPU at 85-91℃ per AIDA64.