Optimizing User Experience with Cookie Consent, A Layered Loading Approach
The Challenge: Balancing Consent and Performance
Modern websites often face a critical challenge: providing a seamless user experience while adhering to privacy regulations that require obtaining user consent for cookies and tracking. Cookie consent banners, while necessary, can negatively impact perceived page load performance and user interaction if not implemented carefully. This post explores a strategy to mitigate these negative impacts by employing a layered loading approach.
Specifically, we aim to address the following problems:
Perceived Delay: The time it takes for the user to interact with the core page content can be significantly delayed while waiting for consent banners (e.g., OneTrust) to load and render.
Layout Shifts: Consent banners can cause disruptive layout shifts, where page elements move unexpectedly, leading to a poor user experience.
Resource Contention: Scripts and resources required for consent banners can compete with other critical page resources, slowing down initial rendering.
Our theory is that by strategically layering the loading and rendering of different page elements, we can prioritize the user's ability to interact quickly, even while consent mechanisms are still loading in the background. This approach aims to provide a smoother, more efficient first interaction.
The "3D Layer" Approach: A Solution
To optimize this process, we propose a "3D layer" approach, visualizing the page load as a series of progressive stages:
Minimal HTML for the banner container and a basic background.
A small, optimized brand logo in a simple header (skeleton or placeholder).
Inline critical CSS for this layer.
Purpose:
Get the OneTrust banner visible as quickly as possible.
Provide a minimal UI for the user to interact with.
Establish the initial brand presence.
Implementation:
Inline the CSS required for this layer directly in the <head> to avoid render-blocking requests.
Use a very small, optimized image or SVG for the logo.
Keep the HTML structure minimal and efficient.
Load OneTrust scripts as early as possible, but use techniques to minimize the impact (see below).
Layer 2: Background Loading (Full Page Content)
Content:
The rest of the page's content (images, text, scripts, etc.).
Purpose:
Load the full page content in the background while the user is interacting with the OneTrust banner.
Ensure a smooth transition to the full page after the user makes their consent decision.
Implementation:
Delayed Loading: Use JavaScript to delay the loading of this layer until after the OneTrust banner is rendered. You can use setTimeout() or requestAnimationFrame() to schedule the loading.
Lazy Loading: Implement lazy loading for images and other resources in this layer to improve performance.
Asynchronous Loading: Load all scripts in this layer asynchronously (using async or defer).
Resource Hints: Use resource hints like preconnect, prefetch, and preload to optimize the loading of critical resources in this layer.
The "Moment Between Clicks" (1 Second or More)
The time between when the OneTrust banner is visible and when the user interacts with it presents a valuable opportunity for optimization.
Implementation:
Trigger Loading on OneTrust Render: Use the OneTrust callback function (OptanonWrapper) or a custom event to detect when the banner is rendered. Initiate the loading of Layer 2 as soon as this event occurs.
Progressive Loading During the Wait: If the user takes longer than one second to interact with the banner, we can still continue loading Layer 2 progressively, prioritizing the most critical content first (e.g., above-the-fold content).
Smooth Transition on Click: When the user clicks a button or closes the banner, ensure a smooth transition to the fully loaded page using CSS transitions or animations.
Browser Capabilities and Web Page Properties
This approach leverages inherent browser capabilities:
Event-Driven Loading: Browsers allow you to trigger actions based on events (like the OneTrust banner rendering).
Asynchronous Operations: Browsers can load resources and execute code asynchronously, allowing you to load content in the background without blocking the main thread.
DOM Manipulation: JavaScript allows you to dynamically modify the DOM (Document Object Model) to add or remove elements, change styles, and trigger transitions.
Implementation Considerations
JavaScript Frameworks/Libraries: Consider using a JavaScript framework or library (like React, Vue, or Angular) to manage the loading and rendering of different layers efficiently.
Performance Budget: Set a performance budget (e.g., target LCP and Speed Index) to ensure the page loads within acceptable timeframes.
Testing: Thoroughly test the implementation across different browsers and devices to ensure a consistent experience.
Key Takeaway
The "3D layer" approach offers a viable strategy for optimizing the user experience with cookie consent. By prioritizing initial interaction, leveraging delayed loading, progressive rendering, and smooth transitions, we can minimize the perceived performance impact of consent mechanisms and create a more user-friendly web.
We will explore the implementation details and performance results of this approach in future posts.