To answer the question, JavaScript is 31x faster out of the box on size 1000000 (compared to the 6x claimed in the post). 71x on 10M.
bwasti@bwasti-mbp code % time python3 prime.py
78498
python3 prime.py 3.86s user 0.02s system 98% cpu 3.938 total
bwasti@bwasti-mbp code % time bun prime.js
78498
bun prime.js 0.07s user 0.02s system 74% cpu 0.125 total
