Why does my FPS drop from 55 to 25 during zooms in Cities Skylines II?

Managing a mega-city was great until rapid camera zooms caused frames to crash from 55 to 25, hindering my efficiency. I tried undervolting in BIOS to reduce heat; while it dropped temps by 5℃, the performance loss was severe and stutters became more frequent. I used the GamePP Fan Curve Configuration Panel to shift the curve above 60℃ upward and set a 5s hysteresis time to stop fan cycling. HWMonitor confirmed CPU temperatures stabilized at 75-82℃, and CPU-Z showed frequency stable at 4.2-4.5GHz. GamePP also monitored memory temps at 45-52℃.