I want to do something that a low level hacker could do in 100 clock cycles with hardcoded bit twiddling and some avx-512, but I want to use nodejs, so I'm gonna need at least 100 million clock cycles to parse all the npm modules...

Not sure why you need a whole bunch of npm modules to do bit twiddling in a performance-sensitive lambda function. Sounds like you just don't like Javascript.

Edit: You're spending like 80ms on cold-start of your lambda function, plus network overhead. If you can spare that, you can likely spare the half a millisecond for the 999,900 cycles you're complaining about.