I use Boinc 8.0.4

My CPU has 12 cores.

I have always configured Boinc to use 100% of the cores, and the processing power of each of the cores used by Boinc was around 8% for each of the cores, where a task was completed in an average time of 2 hours.

However, on 03/28/25 Microsoft released the KB5053656 update, where since then the processing power of each of the cores used by Boinc has dropped from 8% to around 2% for each of the cores, where a task is now completed in an average time of 8 hours!

Interesting detail: the cores can only reach 8% if I leave the Boinc window open and MAXIMIZED. If any other window overlaps the Boinc window (for example, an open spreadsheet or an open browser), the processing power of each core drops back to 2%!

Checking the log for Microsoft's KB5053656 update, it mentions the following technical information:

[Task Manager] Task Manager will now calculate CPU usage differently for Processes, Performance, and Users pages. It will use standard metrics to display CPU workload consistently across all pages and align with industry standards and third-party tools. To ensure backward compatibility, an optional column called CPU Utility is available (hidden by default) on the Details tab, showing the previous CPU value from the Processes page.

For a better understanding, here is the Boinc Event Log:

02/04/2025 04:31:04 | | cc_config.xml not found - using defaults
02/04/2025 04:31:04 | | Starting BOINC client version 8.0.4 for windows_x86_64
02/04/2025 04:31:04 | | log flags: file_xfer, sched_ops, task
02/04/2025 04:31:04 | | Libraries: libcurl/8.8.0-DEV Schannel zlib/1.3.1
02/04/2025 04:31:04 | | Data directory: C:\ProgramData\BOINC
02/04/2025 04:31:04 | | Running under account Rieper
02/04/2025 04:31:04 | | OpenCL: Intel GPU 0: Intel(R) UHD Graphics (driver version 31.0.101.4032, device version OpenCL 3.0 NEO, 3158MB, 3158MB available, 461 GFLOPS peak)
02/04/2025 04:31:04 | | Windows processor group 0: 12 processors
02/04/2025 04:31:04 | | Computer name: Notebook
02/04/2025 04:31:04 | | Processor: 12 GenuineIntel 12th Gen Intel(R) Core(TM) i5-12450H [Family 6 Model 154 Stepping 3]
02/04/2025 04:31:04 | | Processor features: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush acpi mmx fxsr sse sse2 ss htt tm pni pclmulqdq ssse3 fma cx16 sse4_1 sse4_2 movebe popcnt aes f16c rdrandsyscall nx lm avx avx2 adx gfni vaes vpclmulqdq tm2 pbe fsgsbase bmi1 smep bmi2
02/04/2025 04:31:04 | | OS: Microsoft Windows 11: Professional x64 Edition, (10.00.26100.00)
02/04/2025 04:31:04 | | Memory: 7.71 GB physical, 18.36 GB virtual
02/04/2025 04:31:04 | | Disk: 237.62 GB total, 29.39 GB free
02/04/2025 04:31:04 | | Local time is UTC -3 hours
02/04/2025 04:31:04 | | No WSL found.
02/04/2025 04:31:04 | World Community Grid | Computing prefs: from World Community Grid (last modified 17-Feb-2025 16:41:22)
02/04/2025 04:31:04 | World Community Grid | Computing prefs: computer location unspecified; using default
02/04/2025 04:31:04 | | Reading preferences override file
02/04/2025 04:31:05 | | Computing preferences:
02/04/2025 04:31:05 | | - When computer is in use
02/04/2025 04:31:05 | | - 'In use' means mouse/keyboard input in last 1.00 minutes
02/04/2025 04:31:05 | | - don't use GPU
02/04/2025 04:31:05 | | - max CPUs used: 12
02/04/2025 04:31:05 | | - Use at most 100% of the CPU time
02/04/2025 04:31:05 | | - suspend if non-BOINC CPU load exceeds 75%
02/04/2025 04:31:05 | | - max memory usage: 5.78 GB
02/04/2025 04:31:05 | | - When computer is not in use
02/04/2025 04:31:05 | | - max CPUs used: 12
02/04/2025 04:31:05 | | - Use at most 100% of the CPU time
02/04/2025 04:31:05 | | - suspend if non-BOINC CPU load exceeds 75%
02/04/2025 04:31:05 | | - max memory usage: 6.94 GB
02/04/2025 04:31:05 | | - Leave apps in memory if not running
02/04/2025 04:31:05 | | - Store at least 0.40 days of work
02/04/2025 04:31:05 | | - Store up to an additional 0.80 days of work
02/04/2025 04:31:05 | | - max disk usage: 15.00 GB
02/04/2025 04:31:05 | | - (to change preferences, visit a project web site or select 'Options / Computing preferences...' in the Manager)
02/04/2025 04:31:05 | | Setting up project and slot directories
02/04/2025 04:31:05 | | Checking active tasks
02/04/2025 04:31:05 | climateprediction.net | URL https://climateprediction.net/; Computer ID 1554512; resource share 100
02/04/2025 04:31:05 | Rosetta@home | URL https://boinc.bakerlab.org/rosetta/; Computer ID 6304742; resource share 100
02/04/2025 04:31:05 | SiDock@home | URL https://www.sidock.si/sidock/; Computer ID 66572; resource share 100
02/04/2025 04:31:05 | World Community Grid | URL http://www.worldcommunitygrid.org/; Computer ID 8808185; resource share 100
02/04/2025 04:31:05 | World Community Grid | Not using Intel GPU: project preferences

One quick check....
I recently had the cpu clock speed drop from ~4GHz to ~1GHz for no apparent reason. The symptoms were similar to those you describe, resetting the Windows power schedule back to "maximum performance" instead of "optimum performance" cured the problem.

Excellent!

It IMMEDIATELY solved the problems I was facing with Microsoft's KB5053656 update, which for some reason CHANGES Windows preferences without your permission!

Very grateful for the prompt response and solution!