forEach() incurs a function-call overhead unless you optimize it away in a compiler. So the idea a loop would be faster by some multiplier is quite plausible.

forEach() incurs a function-call overhead unless you optimize it away in a compiler. So the idea a loop would be faster by some multiplier is quite plausible. To get an order of magnitude in difference, you'd have to construct a special case. I've seen a multiplier of about 3, but not 16. As an aside: you use forEach() over for loops because most array processing operates on small arrays, where the marginal improvement of using a loop is limited. If you have a large array, you will eventually switch to a for loop if the loop body is relatively small. Likewise, when the request size is small, JSON works fine. But when your requests grows in size, the JSON overhead will eventually become a problem which needs a solution. The underlying consideration is Amdahl's law.