As you might know, &os2; is a "multithreading" operating system, which means that a program can execute several tasks simultaneaously. &xwp; uses its "Worker" thread (which is just a stupid, not a technical description) to prevent certain time-consuming tasks from blocking your system. If &xwp; processed these tasks without the Worker thread, the WPS would not react to anything until the task is completed.
The Worker thread runs at "idle time" priority, which means that it only starts working
if your system has nothing else to do. This way, your system is not slowed down at all
although some time-consuming tasks might be performed in the background.
Note that the Worker thread does some things which are not documented by IBM, especially keeping track of all objects that the WPS keeps in its internal buffers. If you feel that &xwp; is not working properly, you might try to disable the thread on the "Paranoia" page.
Among other things, the &xwp; worker thread is responsible for the following: