> fire those that don't perform up to expectations quickly.
This attitude is why I haven't been recruited. I have 10 years at big tech and companies expect me to jump ship with the threat of getting fired if I don't immediately live up to expectations (even if I'm confident that I will, but I'll never know how high your expectations are until it's too late). Add on wild take home assignments on top of my full time job and (typically) less pay than big tech.
It's simply not worth the trouble.