Choosing a JavaScript framework to create SPA for a poor performed endpoint

I am trying to make an intranet based JavaScript App which can receive and submit data via API. However, my issue is the server also accessed remotely and performance is very poor.

I have studied the following finding ( http://ift.tt/1KuGzG6 ), however still I am not sure which JavaScript framework to choose or even use any JavaScript framework at all. Any input is appreciate it.