Thursday, 13 August 2015

Did I Click That? or What's up with the Browser User Experience on Slow Network Connections

My Network is Slow

For some reason, right now, there is an awful lot of time between my clicking on a link in a web page and any content displaying in my browser. Things are wrong, things are going wrong: it seems that my ADSL network is at a crawl, that DNS queries are incredibly slow, and overall round trip latency even to a server just across the city is awful.

How wrong? Well, I'm writing from Sydney and browsing the Sydney Morning Herald home page (251 HTTP requests, 6,106KB) and it is taking 8 seconds to reach a page load event. Following a link from the home page (Commonwealth Bank customers say double charges not refunded), I see (an incredible) 340 requests and a further 10,467KB downloaded - with a 6 second delay until I see content.

The purpose of this missive is not to complain about the absurd weight of the two pages cited, but to discuss the user experience during the (seeming interminable) wait for content. Since I use Firefox as my default browser, I'll (mostly) confine my comments to that browser, although my comments may be applicable to other browsers - mobile and desktop.

Did I Click That?

As noted, what's happening right now when I click on a link is, well, nothing much. I can't do much about my network, but the issue of nothing much happening at all might be improved upon.

Let me explain by walking through my actions and Firefox's response when viewing articles on the SMH website:
  1. I move my mouse over an article link;
  2. my mouse cursor changes, the anchor tag for the link is underlined as I hover over it and the title specified in the anchor is shown (all from HTML/CSS/JS);
  3. the URL associated with the link is shown in a small, animated, floating status bar overlay in the bottom left of the browser window;
  4. I click my mouse to follow the link - nothing changes between the mouse down and mouse up (again, HTML/CSS - i.e., no CSS :active selector on the SMH website);
  5. as I release the mouse button the link turned grey (CSS :visited selector at a guess);
  6. the tab in my browser changes from showing the page title to displaying an animated 'throbber' alongside the word "Connecting" and the status bar changes according to page load state - for example, "Waiting for", "Read" and so on;
  7. a few seconds later, the tab changes, showing the title of the new page as the browser receives and parses the HTML head element from the server (like I said, things are wrong...); and finally,
  8. some time afterwards, the page renders and the 'throbber' icon is replaced by a favicon for the site.
Chrome does something different, but you have to be observant to note that it shows the domain name ( when it is in the 'connecting' state and it also shows various 'processing' messages in its status bar during page load.   On closer inspection, Firefox does almost exactly the same thing.

Here's a screenshot of Firefox on a Mac showing a page load in progress, with the tab-bar 'throbber' and status bar both highlighted.
Firefox's loading 'throbber' and status bar during a page load.

Given my slow connection, my experience of clicking a link is poor - it's difficult to understand what's happening.

Why so? My eye and therefore my focus is directed to the link that I clicked, not the 'throbber' in the tab bar and not on the status bar.

Given a slow connection, in order to verify that I have actually clicked on a link, my eye has to scan up to the top of the page and then across in order to locate the tab containing the throbber. Alternatively, my eye can scan to the bottom left of the page. Either way, on my slow connection it is not immediately apparent what the browser is up to, leaving me in a state of cognitive dissonance - I clicked that link, didn't I?

Experimenting on Children

As I write this, I have been careful to control my own behaviour. In particular, I have made sure that I click on links once and only once. That's because I know that, just like a pedestrian crossing where pressing the button multiple times does not make the lights change faster, the page won't load any faster if I click the link lots of times. I tell my kids this, but they press the button at the crossing fifty times and a simple experiment this morning reveals that they do exactly the same thing when faced with links that do not result in near instantaneous page loads.

Unlike pedestrian crossings, clicking the link on the web page multiple times does change the outcome. A quick look in the developer tools (Chrome) shows that when the littlies repeatedly click on the same link, outstanding network requests are cancelled.

In an HTTP/1.1 world, this is bad news. I mean really, really bad news for performance. This is because a cancelled request results in a torn down connection (TCP close and all that). Only to be re-established and the same HTTP request re-sent. (In the interests of balance I should add that, networks being what they are, this strategy sometimes works.) I should also add that in an HTTP/2 world, the cost is nothing like as great but it still exists, particularly in the case of network that's just plain slow.

A Modest Proposal

At the risk of stating the obvious, sites should do what they can with HTML/CSS/JS available to them to provide appropriate cues to the user regarding followed links and progress. That's not what this proposal addresses, however. I am making a suggestion about what the browser might do during a page load and is thus outside of the realm of normal HTML/CSS/JS.

From a product perspective, I believe that changing the experience of page loads can improve the user's understanding of what just happened and, by so doing, reduce the number of false reloads which, in turn, might actually improve performance on slow networks.

As noted earlier, the state of the art is a throbber in the tab bar and a part-time status bar. The key change I suggest is to (drastically) change the way that page loading state is conveyed. If we accept that the user expects something to happen immediately on clicking a link, then it is reasonable to use the entire browser window's drawing area to convey feedback about the page load operation. Users are accustomed to modal progress spinners in their mobile apps and I am proposing something similar, but writ large:

It's clear that a link was clicked, a page is loading, and the most common options are clearly accessible to the user.

Looking past the fact that I just threw this together using Gimp and Powerpoint, there are a number of product requirements here:
  1. The act of clicking on a link that navigates away from the current page should result in immediate unequivocal feedback irrespective of page design, the speed of the network, remote server, etc. (More on 'immediate' in moment.)
  2. Information from the anchor URL and title in the followed link should be used to provide feedback about what page is being loaded.
  3. Navigation away from a page is immediate and so all other links on the page should be disabled.
  4. The user should be provided with a simple means to cancel the page load operation and go back to the prior page.
  5. Because sometimes networks will be networks, a means to cancel a slow request and restart it should be provided. 
Arguably the browser already covers off on points 1, 2, 4 and 5.  Therefore, I am only arguing for a change in how this information is presented.

In practice, this might work as follows:
  • The user clicks a link to navigate away from the current page.
  • An interstitial loading page is inserted into the tab comprised of:
    • a background image created from a screenshot of the page being unloaded, with a Gaussian filter applied, is used to indicate that links cannot be followed during page-load. (I chose a Gaussian filter because, hey, why not?);
    • an animated throbber echoes that in the tab bar;
    • the title of the page being loaded (from the anchor element) allows the user to intervene early in the case where the wrong link is clicked;
    • the domain name of the server being contacted is prominent and may assist the user in an early bail-out;
    • a button that provides the user with a means to go back to the prior page; and,
    • a button that allows the user to reload the page.
  • Immediately on receipt of the head element for the new page, the link title is updated in the interstitial and tab bar (so you know you're being rickrolled, just before you really are).
  • The interstitial page is removed and replaced with the new page contents as soon as enough content has been retrieved from the network.  They key requirement here is to avoid replacing the interstitial with a blank page during slow loads.  I'm aware of how hard this may be to implement, what with CSS + JS but see no harm in asking.
In order to cater for fast page loads, the creation of the interstitial might be staggered. On navigation to a new page:
  • Links on the existing page are immediately disabled.
  • The interstitial is immediately created containing a blurred copy of the prior page but with the other interstitial UI elements hidden.
  • Some time later - say 500ms - the throbber, text and button elements are made visible in the interstitial.
Whatever the new UI does, it should not degrade the user experience of fast loads, that is.

At this point, my imagination is galloping off - timing of the creation of the interstitial might be varied depending on whether a connection to the host is already open, or whether the link is to the same domain as the page being unloaded. I use a range of apps such as JIRA where one page looks very much like another. In this case, the bluring and redrawing of near identical pages during navigation might be distracting. Again, timing is key. Animation may be useful. I should stop - my point is that immediate might mean in the blink of an eye.  In summary, I think that this idea will be useless if the timing of the presentation of the interstitial is wrong.

HTTP GET requests require no further discussion. Since POST requests are not idempotent, they must work as they currently do, that is, if the user retries a request, they must be warned that information will be submitted twice.

For the avoidance of doubt, I believe this might work for normal links but not for JavaScript.


In the world of mobile apps, it is common to provide a modal 'spinner' that is displayed in response to a user action to signify that the app is busy, for example whilst waiting for an operation like a network request to complete.  This idea expands upon this.

Utilising the whole of the browser window in order to provide feedback during slow page loads may provide an improved user experience and possibly even lead to modest improvements in load time outcomes.  I reason that the idea is equally applicable to mobile as it is for desktop browsers.

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