The “Minimize main-thread work” error in web development is a performance issue that occurs when the main thread of a browser is overwhelmed with tasks, leading to slow loading times and a poor user experience. To fix this error, there are several steps you can take:

1. Defer the loading of non-critical resources: Non-critical resources such as images and scripts that are not needed for the initial render of a page can be deferred until after the page has loaded. This can help to reduce the amount of work that the main thread needs to do.
2. Optimize your images: Large image files can slow down your website. Optimizing images by compressing them can reduce their file size and improve load times. You can use tools like TinyPNG or Kraken.io to optimize images.
3. Minimize the use of synchronous JavaScript: Synchronous JavaScript can block the main thread, leading to slow loading times. To reduce this, you can use asynchronous JavaScript or web workers to move tasks to a different thread.
4. Use a Content Delivery Network (CDN): A CDN is a network of servers located in different regions that can deliver content to users based on their geographic location. Using a CDN can reduce the load on your server and improve the speed of your website.
5. Use browser caching: When a user visits your website, their browser stores a copy of the files on their computer. This can reduce the load time for repeat visitors, as their browser can retrieve the cached files instead of requesting them from the server.
6. Minimize the use of large libraries: Large libraries such as jQuery can slow down your website. To reduce this, you can use smaller libraries or write your own code.
7. Use code splitting: Code splitting can help to break up your JavaScript code into smaller chunks that can be loaded on demand. This can help to reduce the amount of work that the main thread needs to do.
8. Use performance monitoring tools: Tools such as Lighthouse and WebPageTest can help to identify areas of your website that are causing performance issues. You can use this information to improve the performance of your website.

By following these steps, you can reduce the amount of work that the main thread needs to do and improve the performance of your website. Keep in mind that this is a continuous process, you should always monitor the performance of your website and continuously look for ways to improve it.