Why Web Pages Don't Immediately Show Text - Understanding Rendering

The Shift in Webpage Loading Patterns

Observant web users may have detected a change in how webpages render. Increasingly, images and the overall layout appear before the textual content loads.

This is a notable departure from the loading sequences common during the 1990s, where text typically appeared first.

Understanding the Modern Approach

The current trend prioritizes a faster perceived load time. By displaying visual elements early, websites create the impression of responsiveness, even if the full text isn't immediately available.

This technique leverages the human tendency to quickly assess a page's visual appeal.

Source of the Information

This explanation originates from a question and answer exchange on SuperUser.

SuperUser is a segment of the larger Stack Exchange network, a collection of collaboratively edited question and answer websites.

Why the Change?

The shift is driven by user experience (UX) considerations. A visually complete, albeit temporarily text-light, page feels faster than a blank page slowly filling with text.

Modern web development practices and browser optimizations facilitate this approach.

The Stack Exchange Community

Stack Exchange provides a platform for users to ask and answer technical questions.

Its community-driven format ensures a wealth of knowledge and diverse perspectives on a wide range of topics.

Understanding Delayed Text Rendering on Websites

A SuperUser user, Laurent, has observed a noticeable shift in how web pages load. He’s questioning why text often appears to load after other elements, a reversal of the typical loading order experienced in the past.

Laurent’s Observation

Laurent describes a situation where website backgrounds, images, and other visual components render initially. However, the text content remains hidden, gradually appearing in sections over time.

He points out that this is a change from the older web experience, where text was prioritized and displayed promptly, followed by the loading of images and other design features.

The Core of the Issue

This phenomenon is becoming increasingly common, and it’s particularly noticeable on slower internet connections, as Laurent correctly identifies. But what’s driving this change in loading behavior?

Modern Web Technologies and Rendering Priorities

Several modern web technologies contribute to this altered loading sequence. CSS and JavaScript play a significant role.

• CSS Prioritization: Websites often employ complex CSS rules to control the visual presentation of content. Browsers must download and parse these stylesheets before they can accurately render the text.
• JavaScript Execution: Many websites rely heavily on JavaScript for dynamic content and interactive features. If JavaScript code is blocking the rendering of the page, text display will be delayed until the script has finished executing.
• Font Loading: Custom fonts are frequently used for branding and aesthetics. The browser must download these fonts before the text can be displayed with the correct styling.

Essentially, the browser is prioritizing the visual layout and styling before displaying the textual content. This contrasts with the earlier web, where simpler designs allowed for faster text rendering.

The Impact of Slow Connections

While this behavior is present on faster connections, it’s significantly exacerbated by slower internet speeds. The time required to download CSS, JavaScript, and fonts increases, leading to a more pronounced delay in text rendering.

Therefore, Laurent’s observation about a slow connection accentuating the problem is accurate. The bottleneck becomes more apparent when resources take longer to arrive.

In conclusion, the shift in loading order isn't due to a single "new technology" but rather a combination of evolving web development practices and the increasing complexity of modern websites.

Understanding Delayed Font Loading

A detailed explanation from SuperUser contributor Daniel Andersson clarifies the reasons behind why fonts sometimes appear to load slowly on webpages.

The Shift to Web Fonts

Historically, websites relied on fonts already installed on a user’s computer. Designers would specify a font-family list, like font-family: Arial, Helvetica, sans-serif;, ensuring a fallback option was available if the preferred font wasn’t present.

The advent of web fonts, commonly in WOFF format and often sourced from services like Google Web Fonts, changed this paradigm.

How Web Fonts Impact Rendering

Web fonts allow designers to utilize custom fonts without requiring users to have them pre-installed. However, this introduces a delay.

Browsers must first download the font file, then load it, and finally render the text. This process—download time, loading time, and render time—can result in a noticeable delay before text becomes visible.

The "Flash of Unstyled Content" (FOUC)

This delay is often experienced as a "flash of unstyled content" (FOUC), or more specifically, a "flash of unstyled text" (FOUT).

One example cited is the national newspaper Dagens Nyheter, which uses web fonts for headlines but not body text; users typically see the body text first, followed by the headlines after a short delay.

Browser-Specific Behavior

Different browsers handle this situation differently. WebKit-based browsers (like Chrome and Safari) avoid FOUT by initially hiding text that relies on web fonts, even if the font is cached.

Even cached web fonts can cause a render delay, dependent on the amount of text and other factors.

Firefox and Internet Explorer

As of certain versions, Firefox no longer exhibits FOUT, initially displaying text with a fallback font for a brief period before loading the web font.

Internet Explorer 9, however, does experience FOUT, while WebKit browsers are implementing patches to display fallback text after a short delay (0.5 seconds).

Mitigation Strategies

While this explanation focuses on the cause of the issue, solutions like using webfontloader exist to minimize the impact of delayed font loading. Further details can be found in resources like Paul Irish’s post on FOUT.

Further Discussion

For those interested in exploring this topic further, the original discussion thread on Stack Exchange offers additional insights and perspectives.