Dmytro Mezhenskyi - The Hidden Cost of Zone.js and What Replaces It | NG Belgrade Conf 2026

Zone.js has been a core part of Angular’s change detection for years. At the same time, it introduces real trade-offs: more challenging debugging, unpredictable performance, increased bundle size, and additional runtime overhead. In this talk, we’ll start by examining the price we pay for using Zone.js and what practical benefits zoneless mode brings in return: improved performance characteristics, a clearer mental model, and an enhanced developer experience. After that, we’ll take a short look under the hood of Angular’s zoneless mode. You’ll see how Angular triggers change detection without Zone.js, the role of the ChangeDetectionScheduler, and how the framework knows which exact parts of your application view need to update. By the end of the talk, you’ll have a clear understanding of why zoneless exists, how it works at a high level, and what changes for you as an Angular developer.