Curious.
λ timer64 flac_clang20.exe -8 -f Falco.wav
flac 1.5.0
Copyright (C) 2000-2009 Josh Coalson, 2011-2025 Xiph.Org Foundation
flac comes with ABSOLUTELY NO WARRANTY. This is free software, and you are
welcome to redistribute it under certain conditions. Type `flac' for details.
Falco.wav: WARNING: there is data trailing the audio data. Use --keep-foreign-metadata or --ignore-chunk-sizes to keep it
Falco.wav: wrote 479398390 bytes, ratio=0,662
Kernel Time = 0.875 = 7%
User Time = 11.093 = 92%
Process Time = 11.968 = 99% Virtual Memory = 15 MB
Global Time = 12.033 = 100% Physical Memory = 18 MB
λ timer64 flac_gcc15.exe -8 -f Falco.wav
flac 1.5.0
Copyright (C) 2000-2009 Josh Coalson, 2011-2025 Xiph.Org Foundation
flac comes with ABSOLUTELY NO WARRANTY. This is free software, and you are
welcome to redistribute it under certain conditions. Type `flac' for details.
Falco.wav: WARNING: there is data trailing the audio data. Use --keep-foreign-metadata or --ignore-chunk-sizes to keep it
Falco.wav: wrote 479398390 bytes, ratio=0,662
Kernel Time = 0.625 = 4%
User Time = 14.546 = 95%
Process Time = 15.171 = 99% Virtual Memory = 15 MB
Global Time = 15.226 = 100% Physical Memory = 21 MB
And this is official flac 1.5.0
λ timer64 flac.exe -8 -f Falco.wav
flac 1.5.0
Copyright (C) 2000-2009 Josh Coalson, 2011-2025 Xiph.Org Foundation
flac comes with ABSOLUTELY NO WARRANTY. This is free software, and you are
welcome to redistribute it under certain conditions. Type `flac' for details.
Falco.wav: WARNING: there is data trailing the audio data. Use --keep-foreign-metadata or --ignore-chunk-sizes to keep it
Falco.wav: wrote 479398390 bytes, ratio=0,662
Kernel Time = 0.812 = 5%
User Time = 13.265 = 93%
Process Time = 14.078 = 99% Virtual Memory = 15 MB
Global Time = 14.147 = 100% Physical Memory = 18 MB
Why such a difference? I have R5 3600 CPU, mostly at defaults. 3 seconds for an image file.