The grey box on the house is a part of the NTD rather then a Node which are the cabinet boxes on the street...
but that isn't really relevent in order to help you with your question, you would need to give us more information.
If you check http://speedtest.net and do a test, what speed is it showing for your connection?
When they talk about the connection speed, that will be your best idea of the actual connection speed.
But as for websites loading there are a number of componants that can play part in the speed you actually experience on the device itself.
I am assuming since you are using an MacBook Air and it only has Wi-Fi that you are using Wi-Fi to connect, so it could be a Wi-Fi congestion issue, Wi-Fi runs over wireless frequencies, and if a lot of connections are using the same frequency it can become congested and lead to interference between connections.
It also depends on the website you are accessing and their capabilities, so say you access my website, but my website is only capable of sharing information at 5Mbps, it would make no difference if your speed was 5Mbps or 50Mbps it will load the same as the website is not capable of sharing any faster... it can also lead to slower loading if you are connecting to websites which are hosted in other countries as the request has to go through more points to reach the website and then come back...
If you come back with the speed test result, it will be a great place to start... and we can see if we can suggest things to try and help you out from there.