Well there's mistake No.1 Using HD images.
Don't you know that majority and I would say that >95% of users on on video screens that only go as high as 96 or 120 dpi.
At most, you need a 1024 x 768 @ 120 dpi and compressed with JPG at around 76,79 or 81 compression ratio depending on how much detail you want to retain. Higher compression = less resizeability as in upscale.
If you trawl youtube, you will find plenty of videos that draws issues over todays programmers, its been shown that computers, although faster are no faster in toerms ofg processing through put because programming today is bloat.
Long gone is the ideal to make every bit count, that art has been lost and people only write bloat, use bloat in their sites and no regard for the simple fact that broadband, despite its wide spread use, majority of the world (even the US has 2 or 3% of users on dialup!!!) on a dial up service that is dependent on how far you are from the exchange.
So keep in mind, size is proportional to the speed and large data sets = slow loading site.