The problem is this:

In the basesorter.py we have a default_job_kwargs that by default sets n_jobs to -1 (here). My suggestion is to remove this and warn if the sorter requires_binary_data and n_jobs=1, saying that this might make things slower.

Another option (and maybe complementary) is to set default n_jobs globally to something like 0.5.

What do you think @zm711 ?

In the basesorter.py we have a default_job_kwargs that by default sets n_jobs to -1 (here). My suggestion is to remove this and warn if the sorter requires_binary_data and n_jobs=1, saying that this might make things slower.

I think this sounds right! I don't think we should change the n_jobs without the user knowing!

Another option (and maybe complementary) is to set default n_jobs globally to something like 0.5.

Yeah I'm not sure what the fair value for this would be. Like 0.9 or 0.8 would probably be safe to leave a core or two behind whereas 0.5 would leave more stuff behind. But yeah I think changing the default from -1 would be nice.