Rcpp - generate multiple random observations from custom distribution

This question is related to a previous one on calling functions within functions in Rcpp.

I need to generate a large number of random draws from a custom distribution, in a way similar to rnorm() or rbinom(), with the additional complication that my function produces a vector output.

As a solution, I thought about defining a function that generates observations from the custom distribution, and then a main function that draws n times from the generating function via a for loop. Here below is a much simplified working version of the code:

#include <Rcpp.h>
using namespace Rcpp;

// generating function
NumericVector gen(NumericVector A, NumericVector B){
  NumericVector out = no_init_vector(2); 
  out[0] = R::runif(A[0],A[1]) + R::runif(B[0],B[1]);
  out[1] = R::runif(A[0],A[1]) - R::runif(B[0],B[1]);
  return out;
}

// [[Rcpp::export]]
// draw n observations
NumericVector rdraw(int n, NumericVector A, NumericVector B){
  NumericMatrix out = no_init_matrix(n, 2);
  for (int i = 0; i < n; ++i) {
    out(i,_) = gen(A, B); 
  }
  return out;
}

I am looking for ways to speed up the draws. My questions are: is there any more efficient alternative to the for loop? Would parallelization help in this case?

Thank you for any help!