You won’t see any real performance comparisons because any benchmark related to kdb+ is completely restricted by its company. J without the database (Jd) is dua

You won’t see any real performance comparisons because any benchmark related to kdb+ is completely restricted by its company. J without the database (Jd) is dual licensed with gpl as an option, so you can try to compare the base language by yourself for your application. But Jd again is free only for non-commercial use only. Those shakti downloads seems to be fully functional.