Comment by immibis

Recently I stumbled across the online catalog for Segor Electronics (segor.de I think? Google it. Only in German. They're not paying me to post this)

It's extremely fast. Super duper fast. And a quick look at the network debugging tab shows why: it loads the shop's entire catalog data (about 3 megs) upfront, and the entire application runs locally with not a single request until you buy something. Now that's efficiency.

Really. Go to their website, clock on KATALOG and click some random buttons, pick a product at random, add it to your cart, remove it from your cart.

The product images are the only things that aren't pre-loaded.