I tried installing SPAdes via Homebrew (https://formulae.brew.sh/formula/spades#default) yesterday, and was surprised by the long time the genome assembly took (about 2,5 hours instead of 20-30 minutes). Turned out SPAdes used only 1 thread instead of 16.
0:00:00.000 5M / 5M INFO General (main.cpp : 78) Maximum # of threads to use (adjusted due to OMP capabilities): 1
After a long time trying to set up a correct number of OpenMP threads manually, with no luck, I contacted the SPAdes support team and was recommended to download it from their original site (https://cab.spbu.ru/software/spades/). And it worked just fine, using all the 16 threads in my CPU without any options.
So I just wanted you to know, that the SPAdes formulae is somehow broken with multithreading disabled. I hope this can be solved, as using Homebrew turned out to be very convenient=)
Please let me know, if I can provide additional info, that can be useful to solve this issue.