neowin[.]net/news/report-microsoft-defender-is-hogging-intel-cpus-while-amd-ryzen-remains-unscathed/
techpowerup[.]com/295877/windows-defender-can-significantly-impact-intel-cpu-performance-we-have-the-fix
Bottom line: "... a Core i9-10850K running at 5.00 GHz all-core loses 1000 Cinebench points (or 6%). Such a performance loss has been reported by owners of Intel Core 8th, 9th, 10th and 11th Gen, both desktop and mobile CPUs, on both Windows 10 and Windows 11. AMD processors are not affected."
The underlying issue that costs so much performance is that Windows Defender will randomly start using all seven hardware performance counters provided by Intel Core processors...... Windows Defender on the other hand will set these counters to "mode 2", at what looks like random intervals, for random durations of time. This can happen when a computer first boots up or it can happen at any time after that. While Windows Defender is running in the background, it can start and stop or continuously try to change these counters to mode 2 at any time. Just to clarify, the performance loss will happen even without any monitoring software running—Defender will still use excessive CPU time.
The issue is not with the Intel hardware, as setting the same timers as Windows Defender manually has no negative performance impact. Also, if these counters are manually overwritten, Defender detects that, immediately stops whatever it is doing and performance returns to normal—without any negative effect on the ability to detect viruses in real-time.
There are two ways to go about mitigating this performance loss permanently. You could disable Windows Defender Real-time Monitoring, which is highly not recommended due to the security implications; or you could use the latest version 9.5 of ThrottleStop, which has a feature in the "Options" window, called "Windows Defender Boost." Ticking this ensures maximum performance and accurate Core Effective Clock monitoring in all applications whether Windows Defender real-time protection is enabled or not.
techpowerup[.]com/download/techpowerup-throttlestop/