Hopefully this will prompt other browser developers to take latency more seriously as a means of improving performance. So far I’ve only seen Opera do something similar, but Firefox (at least with version 2) would patiently wait for each JS/CSS item before moving on.

If you do, you should also insert a visible element informing the user that the page shown only has partial content. A red strip (or even better, an alternating construction yellow/black strip) at the top of the viewport… Because the “broken document” icon Navigator used to display only applies to unloaded images and many other invisible elements in a page could be missing and render the page dysfunctional (like scripts) where the “broken document” icon would not be visible.

What happens is that rendering stops, and in the Actiivty window some js file from an ad network is listed as “0 bytes of ?”. If I double click the line in the Activity window, a new window opens with the (seemingly) complete contents of the file, but the original entry in the Activity window remains at “0 bytes of ?”, and the original page does not resume rendering.

Here is an example of a page that shows the problem:

http://politiken.dk/

It doesn’t happen on a Netlink router (with Airport as the Wi-fi router) on a different ADSL network.

This optimization seems to have improved things, but it still happens quite often, so I get the suspicion that there are timing-related reasons for these pages not rendering. Reloading the page a couple of times finally shows it.

Firefox does not seem to have the problem.

Okay, so the problem arises when my arms get tired. I bring the laptop down to my lap, and find Safari showing a blank white page, while the status bar says “loading news.com; completed 22 of 105, 16 errors encountered” in the status bar. I sigh, wait a few seconds, hit reload and lift up the computer again.

What I would *really* like is if WebKit would just show me whatever it has downloaded already, instead of a white page. I don’t care about FOUC if that ‘flash’ lasts 3 minutes. At least I get to read something in that time. Often the laptop simply loses the wireless connection completely, in the middle of a page load, and WebKit just sits there dumbly waiting for data that’s never going to arrive. Can dumynet simulate this too?

Looking at the network inspector, there is only a slight improvement in actual load time (0.3 seconds or so, it fluctuates), but the javascript and css files are loading much earlier. More importantly, the page is drawing to the screen almost 2 seconds faster in the nightly build than in Safari 3.1 (just over 2 seconds for nightly, just over 4 seconds for Safari 3.1).

Good work guys!