If you're putting jQuery in your main application bundle then it has to be parsed and executed before you can do anything. That's not the same as an equivalent

If you're putting jQuery in your main application bundle then it has to be parsed and executed before you can do anything. That's not the same as an equivalent sized image which just needs to be decoded and painted. If it's a chat widget hopefully you're loading it separately. I agree that CSS can also be a problem.