gistfile1.sh

> time node ~/tmp/perf-test.js
dynamic

real    0m0.697s
user    0m0.690s
sys     0m0.013s

> time node ~/tmp/perf-test.js static
static

real    0m0.680s
user    0m0.670s
sys     0m0.013s

perf-test.js

#!/usr/bin/env node

function fixRegex(re) {
  var source = re.source;
  var flags = (''+re).slice(source.length+2);
  return new RegExp("^(?:"+source+")", flags);
}

if (process.argv[2] === 'static') {
  console.log('static');
  function re() { return /^a+/; }
}
else {
  console.log('dynamic');
  function re() { return fixRegex(/a+/); }
}

var testStr = 'aaaaaaa'

for (var i = 0; i < 1000000; i += 1) {
  re().exec(testStr);
}