Conflicting Applications: If there are applications (like Opera GX Browser) present on your system, it can massively decrease the system speed, resulting in the issue at hand.Corrupt System Files: If the essential system files of your system have become corrupt due to previous system updates (or a sudden power shut down), then your system can become very slow.Outdated PC Drivers: If the OEM of your system has not updated its system drivers (especially, drivers of Blu-Ray or DVD drives) to be compatible with the Windows version 21H1, it may cause the PC issue under discussion.
If your system is missing such a patch, then it may result in the slowness of your PC.