Textual links should be colored and underlined to achieve the best perceived affordance of clickability, though there are a few exceptions to these guidelines.| Nielsen Norman Group
Flat design is a web-design style that became popular around 2012. It is still widely used today, and its misuse can cause serious usability problems.| Nielsen Norman Group
Whether you adopt a flat-design style or not, interactive components must retain sufficient cues to suggest clickability.| Nielsen Norman Group
Slow page rendering today is typically caused by server delays or overly fancy page widgets, not by big images. Users still hate slow sites and don't hesitate telling us.| Nielsen Norman Group
The total cognitive load, or amount of mental processing power needed to use your site, affects how easily users find content and complete tasks.| Nielsen Norman Group