Is the difference because GTA has more "readable" code?
I have other games that do load up quicker than Twitter, which I do think is damning, but it's not really the point I'm trying to get across here.
But then, you brought up GTA and games, which aren't even apples and oranges with a website. Websites—even the Twitter website—don't require GPUs or dedicated memory, they don't have the advantage of pulling everything from the local hard drive, and yet they actually work as designed, not merely in a low-resolution, low-effects mode on computers more than a couple years old.
And while I wouldn't point out the Twitter home page as remotely fast for a web site, have you actually even looked at it recently? It shows a lot more than just a few tweets and avatars. It's got images, embedded video, etc.
There's definitely another discussion to be had about why web tech is so disastrously slow given what computers are capable of, but it's not worth having here. We're never going to settle that one, and regardless if you are a web guy, you're stuck with JS.
>It's got images, embedded video, etc.
Bad excuse IMO. Lazy load them.