This is an example of the proof of work used in block generation in nano/banano. Made this to understand the pow better this could help you if you looking for that :)
npm install --save git+npm install --save @anzerr/banano.pow
Where to look
If you want to how the pow works look in "libary/pow.js" the other files are just to fork to use the move cores
Around 30 speed
On a i5-4440 @ 3.10GHz I get around
175 kH/s 320kH/s don't know how bad that is compared to other. Probability slow?