1. A computer-implemented method comprising: obtaining an expression including at least an array to which one of an elementwise operator or an elementwise function is applied; starting execution of the expression in a computing environment; weighting the elementwise operator or the elementwise function based on a performance profile, the performance profile pre-computed by measuring a performance of a sample elementwise operator or function on specific hardware prior to the execution of the expression; determining, during the execution of the expression, that a portion of the expression is to be executed in parallel, the determining is based on the weighting and a number of elements in the array; and continuing the execution of the expression in the computing environment by executing a subset of the elements of the array in parallel with one or more additional subsets of the elements of the array.