Comment by lelanthran

> You end up with a really bad waterfall where it can take a long time for a page to load because it's going back to the server constantly, whereas if you did it on the server it would be a single round trip.

These are all static file downloads, though. The first page load will take long, but if these are header/footer type includes, every subsequent page will use the cached file.

It's a trade-off between longer times for landing page and shorter times for every other page. The developer will decide whether or not to make the trade-off.