Is FileMaker the only application you have open at the time?
Do you have just one FileMaker file open or several?
I've seen this on my machine but it appears to be only when I have a lot of stuff open--including a hosted FileMaker file that is frequently and constantly receiving new data. It seems to be a case of FileMaker continually trying to update a background window when other users commit their changes/new records. If I close out some files, the issue goes away.
I've also seen a case where a second application was fighting with FileMaker for system resources. If you have more than one application running, open windows task manager and check memory and CPU percentages to see if any one application is hogging your system resources.