Why does my i5 12600KF freeze during UE5 Matrix shader compilation?

I was thrilled to run the UE5 Matrix demo, but during shader compilation, CPU usage jumped wildly between 40% and 100%, freezing the editor. I tried manually setting affinity in Task Manager, but this caused the compiler to crash immediately, proving the method too crude. I used GamePP Power Plan Switcher for High Performance mode and disabled E-Cores in BIOS. Single-core frequency stabilized at 4.9GHz per Cinebench R23, temps stayed at 72-81℃ per AIDA64, and fan speeds hit 1800-2100RPM via GamePP Sensor. Now I can switch