You built a Gantt chart for your Angular app. It worked great in development with 100 tasks. You demoed it to the team. Everyone was happy. Then someone tested it with a realistic dataset, 5,000 tasks, then 10,000. Suddenly the page takes 8 seconds to render. Scrolling stutters. Dragging a task freezes the browser for a full second. The dev tools profiler turns red across the board. If you've been there, you know it's not just frustrating, it's the kind of problem that gets a project quietly canceled, because "the prototype was fine, why is the real thing so broken?" This post is about why this happens and the four strategies, ranked by complexity, that actually solve it. Why your Gantt chart is slow (the real reason) The instinct is to blame Angular. It's not Angular. Angular is fine. The issue is that Gantt charts are unusually hostile to the way browsers render content , and most Gantt implementations make this worse before they make it better. Let's count nodes.…