Since macOS Sierra or Excessive Sierra, macOS has turn out to be actually, actually sluggish.
Reinstalling El Capitan (even as we speak) solves the problem.
GNU/Linux and Home windows are additionally a lot quicker, extra like El Capitan was.

By slower, I imply twice (or extra) the time to construct a easy C challenge (from 5-6 seconds to 15 seconds), the entire system is absolutely sluggish, I actually suppose that it’s a macOS concern.

For data, I examined primarily with gcc-9 and clang-10 with my faculty initiatives.
I additionally used tcc 0.9.27, constructed from supply, with a dummy make+C challenge, see beneath.

I’ve already tried to reinstall macOS.

I’m not certain about what to do, have anyone ecountered this ?

I would like macOS for the iOS/tvOS toolchain, subsequently I can’t swap.
Switching to a GNU/Linux distro could be good if I might.

If anyone wants extra particular information, don’t hesitate.
Many thanks on your assist !

Issues I examined at all times on the identical laptop with this dummy repo edrflt/build_speed :

tcc 0.9.27, constructed from supply

Ubuntu 20.04 (quick):

make -j5   0,94s person 0,53s system 342% cpu 0,428 whole

Mac OS X Yosemite 10.10 (quick):

make -j5   1,84s person 1,05s system 284% cpu 1,016 whole

Mac OS X El Capitan 10.11 (quick):

make -j5   3,04s person 1,18s system 316% cpu 1,332 whole

macOS Catalina 10.15 (sluggish):

make -j5   6,01s person 3,35s system 193% cpu 4,827 whole

gcc-9

Ubuntu 20.04 – gcc 9.3.Zero from apt

make -j5  10,15s person 4,69s system 361% cpu 4,111 whole
make -j5  10,13s person 4,74s system 357% cpu 4,162 whole
make -j5  10,27s person 4,54s system 359% cpu 4,119 whole

macOS Catalina 10.15 – gcc 9.3.Zero from brew

make -j5  13,95s person 10,55s system 298% cpu 8,204 whole
make -j5  16,91s person 12,81s system 252% cpu 11,752 whole
make -j5  14,05s person 10,81s system 295% cpu 8,412 whole

Notes :

My MacBook Professional is that this one :
MacBook Professional (Retina 13, early 2015) – MacBookPro12,1
i5 5257U – 8GB

I’m completely open to any exams, any suggestion.
I do know I do not know sufficient about low degree OS elements and compilers, subsequently you probably have the time, clarify me like I am 5.
I’ll take any time that will be wanted.
This isn’t in any respect about macOS is best, GNU/Linux is best … no no, that is about “I would like my laptop to get his velocity again”.