Modern web applications are awesome. And complicated. The Javascript libraries that power them today do a lot of work to abstract out the hard parts. Whether using constructs like Virtual DOM, or fancy change detection algorithms, the amount of work that the Javascript library does is only increasing.
Unfortunately, all this work now competes for the same resources that the browser needs, to do things like render a page, or apply styles. In many cases, this makes the browser slow, preventing the web application from attaining its full, smooth experience.
Web workers have been in the browser for a while, but they have mostly been used for engaging demos like adding mustaches in a cat video :)
In this talk, we will explore how mainstream Javascript libraries like React or Angular use Web Workers to get great performance. We will look at quantitative numbers from hundreds of test runs that conclusively show how Web Workers can make apps faster. Finally, we will also look at practical examples to convert existing examples, and the potential limitations of this approach.
I'd try to condense this further - it's a little long - and add a more substantial ending that reiterates the value of what the audience can expect to learn from the session.