How much space do you have on your local hard drive? Are you working in a large file all day without shutting down? What version of Revit are you on? How much memory do you have on your local machine and what are the virtual memory settings? If seems like I have had this before a long time ago when I would run out of memory on my local machine and there was no memory left to process or cache information. Remeber you are still caching all of data you open in all of those views on your local machine.