That sounds like that Bernina Artista application is running at the same low CPU priority (or even lower?) than the boinc projects themselves?

I've never heard of that application, but can you check on the task manager (if it's windows) to see what priority level the Bernina Artista process is running at? If the main process of that application, or any child processes, are running on low priority, give them a boost to normal to see if they run.