lesson 09 - factors affecting ui choice 1 - performance & usability
This page explains how UI performance (speed, responsiveness) and usability (ease of use) are critical factors in creating a successful user interface that users will love.
Fast and Friendly: Why Performance and Usability Are Crucial for a Great UI
(Image: A dynamic picture showing a user looking frustrated at a loading spinner on a screen, contrasted with another user happily and quickly navigating a clean, fast website on their phone.)
When we design a user interface, it's easy to get carried away with making it look amazing. But what if that amazing-looking website takes ten seconds to load? Or what if the buttons are so small you can't tap them? This is where two crucial factors come into play: performance and usability.
🏎️ What is Performance?
Performance is all about speed and efficiency. It’s the technical measure of how smoothly the interface runs. A high-performance UI feels fast, fluid, and light. Key aspects include:
Loading Speed: The time it takes for a website or app to become usable. Studies show that users will abandon a site if it takes more than a few seconds to load.
Responsiveness: How quickly the interface reacts when you tap, click, or type. A delay between your action and the system's reaction is called 'lag' and is a sign of poor performance.
Resource Usage: How much of the device's power the UI consumes. A poorly performing app can drain your phone's battery, use up all your mobile data, or slow down your entire computer.
Designers improve performance by optimising images, writing efficient code, and minimising complex animations.
(Video: Embed a short "website speed test" video from YouTube, showing two websites loading side-by-side, one much faster than the other, to visually demonstrate the impact of performance.)
👍 What is Usability?
Usability is the measure of how easy and pleasant an interface is to use for a human. It’s all about the user's experience. A usable interface is intuitive, clear, and forgiving. Key aspects include:
Learnability: How quickly can a new user figure out how to use it? Do they need a manual, or is it obvious?
Efficiency: Once they've learned it, how fast can they get things done? Are there shortcuts?
Memorability: If a user leaves and comes back a week later, will they remember how it works?
Error Prevention: Does the design stop users from making mistakes? And if they do make one, how easily can they fix it? (e.g., a clear "Undo" button).
Satisfaction: Simply put, is it an enjoyable, stress-free experience?
Designers improve usability with clear labels, logical layouts, large buttons, and helpful feedback.
The Great Trade-Off
Often, performance and features are on opposite ends of a scale. A website with huge, uncompressed images and auto-playing 4K videos might look stunning, but its performance will be terrible. A plain text website will have fantastic performance but won't be very engaging.
The goal of a great designer is to find the perfect balance.
(Animation: A simple animation of a see-saw. On one side is a box labelled "Features & Graphics" and on the other is a box labelled "Performance". As the "Features" box gets heavier and goes down, the "Performance" box goes up, and vice versa.)
For our Majestic Cinema project, this is vital. The interface must look appealing (good usability), but it must also load quickly (good performance) so customers can book their tickets without getting frustrated and going to a competitor.
Last modified: July 8th, 2025
