Why does The Mageseeker drop FPS during team fights on A320M?

In the heat of a mid-lane team fight, my FPS would plummet from 120 to 45 per RTSS the moment effects filled the screen, which is a total disaster. I tried enabling 'Ultimate Performance' in Windows Power Options, but it only added 3 FPS per RTSS while stutters persisted, leaving me feeling anxious. I used the GamePP Process Priority Manager to lock the game's main process to Realtime and restricted background software. RTSS showed frame times converged from a chaotic 14-42ms to a stable 12-16ms, with AIDA64 reporting CPU temps at 62-70℃. Now it's set