I do a certain amount of web design in my day to day work and strive to avoid call outs to external services that often slow down page loading massively, thus making it no faster to view a site on 76mbps than 10mbps. All those calls to Twitter, Facebook and YouTube etc as the page opens can make your website annoyingly slow.
On one site I ended up removing Vimeo, because the call for their precious analytics on the other side of the world was adding 2 seconds to the page opening, which is untenable for an e-commerce site.
A lot of designers haven't yet grasped the concept of focussing their designs more tightly for mobile than desktop and average page weight is considerably higher than a few years ago. A lot of those bells and whistles, such as cool animations place a lot of strain on low end mobile devices.
All of this is beyond your control, unless it's your own site, but I hope this explains to a degree why web pages won't automatically be opening that much faster if you start paying a premium for a 300mbps connection. A large percentage of websites are also hosted on dirt cheap shared hosting packages that are crammed to bursting point, so the resources are really limited and this is particularly bad if you use something like Wordpress.
