Multithreading in Frontend? A Guide to Web Workers

About this talk

JavaScript as a single-threaded language is unable to maximise the full potential of modern CPUs — but Web Workers might change that. This talk at DevBCN 2025 explored the complexities of the JavaScript runtime, event loop, and asynchronous programming to find out whether it is worth stepping into the multithreaded world. By examining the potential benefits and drawbacks of Web Workers through live demos, attendees left with a clear framework for deciding if they are the right tool for their next project.

Key takeaways

• Why JavaScript's single-threaded model limits CPU-bound performance in the browser
• How the event loop and async patterns interact with true parallelism via Web Workers
• Live demo: offloading heavy computation and measuring the impact on frame rate
• When Web Workers are worth the overhead — and when simpler patterns are enough