In heroku dyno console functions are very costly. Thanks to Michel for helping me to identify this http://micheljansen.org/blog/entry/1698. Prepended the following lines in app.js and it increased the speed of the app very much.

nullconsole.js

/*
* Add this as first line to app.js speed up Heroku nodejs application
*/
if (process.env.NODE_ENV === 'production') {
  var nullfun = function () {};
  console.log = nullfun; 
  console.info = nullfun; 
  console.error = nullfun; 
  console.warn = nullfun;
}