A Worker provides a way for you to have code that runs on multiple CPU cores. A Worker achieves this by running its code in a Console app. One or more of these console apps are started based on your Worker settings. Since these run as Console apps, the OS treats them as separate processes and spreads them out amongst available CPU cores.
With today’s multi-core CPU’s it seems that an application made with Xojo running on a single core is somewhat restricting. If you have a lot of data to process, large images to manipulate or other things that could happen in the background, it would seem that with a multi-core machine you could do this faster “if only Xojo would make threads preemptive”. We get a lot of requests for preemptive threads so that people can take advantage of multiple cores.