measure

gistfile1.js

var measure = function(fn, iterations, timeout) {
    iterations || (iterations = 10000);
    timeout || (timeout = 5000);

    var i, end, total;
    var timeoutMsg = "";
    var start = performance.now();
    for (i = 0; i < iterations; i++) {
        fn();
        end = performance.now();
        total = end - start;
        if (total > timeout) {
            timeoutMsg = "[TIMEOUT] ";
            break;
        }
    }

    return timeoutMsg + "Iterations: " + i + ", Avg time: " + total/i + ", Total time: " + total;
};