The speed you feel online often comes down to distance.
Content Delivery Networks keep copies of files on servers near you, so a request is answered nearby instead of from across the world.
A shorter round trip means a video starts sooner and buffers less. The catch is redundancy — the same file on many servers costs more to store.
So when a page loads instantly, it's usually not a faster connection. It's a copy waiting maybe 50 miles away instead of 5,000.