partytown

Focuses the main thread on critical application code by moving non-essential scripts to a web worker, directly addressing performance bottlenecks as stated in the README's goal to 'help speed up sites'.

Enables synchronous third-party scripts to function in an asynchronous web worker environment, a unique feature highlighted in the key features for handling scripts like analytics without breaking functionality.

Loads only when needed, minimizing initial page weight, which is explicitly mentioned in the description as a lazy-loaded library to reduce upfront resource consumption.

Helps reduce main thread blocking, improving metrics like Largest Contentful Paint and Total Blocking Time, aligning with the value proposition of optimizing performance for sites with heavy third-party script usage.